Notice to all participants: In addition to Zoom, the SUSY 2021 Plenary talks will also be broadcast live on Youtube
Since its inception in 1993, the annual SUSY conference has become one of the world's largest international meetings devoted to new ideas in fundamental particle physics. Supersymmetry is one of the most elegant and promising extensions of the Standard Model, with the ability to resolve various puzzles in the Standard Model naturally. Major experimental efforts, including collider searches and dark matter experiments, are ongoing to search for supersymmetry in Nature. However, thus far no definitive evidence of supersymmetry has been found. SUSY 2021 will be dedicated to not only understanding the status of supersymmetry searches at various experiments, but also exploring whether all supersymmetric possibilities are exhausted, and if there exists any well-motivated alternative theories which can also address the issues of the Standard Model. The goal of the International Conference on Supersymmetry and Unification of Fundamental Interactions (SUSY) is to review and discuss recent progress in theoretical, phenomenological, and experimental aspects of supersymmetric theories and other approaches to physics beyond the Standard Model of particles and interactions.
The SBC Collaboration is constructing a 10-kg liquid argon bubble chamber with scintillation readouts. The goal is to achieve 100 eV nuclear recoils detection with near-complete discrimination against electron recoil events. In addition to a dark matter search, SBC targets a CEvNS measurement of MeV-scale neutrinos from nuclear reactors. A high-statistics, high signal-to-background detection would enable precision searches for physics beyond the standard model. In this talk, I will present the physics reach of the SBC detectors and the advantages of using such technology. I will also discuss the progress towards the construction at Fermilab to test the sub-keV threshold performance and at SNOLAB for the search of dark matter.
The dark sector may be as rich and varied as the standard model. Twin Higgs models, which explain the little hierarchy problem, provide a compelling and predictive realization of such a dark sector, where the standard model field content is copied in a hidden sector. I show how spontaneously breaking the twin color can naturally lead to asymmetric dark matter and baryogenesis in addition to solving the hierarchy problem. I outline how this scenario can be tested at the LHC and future colliders.
Primordial black holes (PBH) are a natural and generic dark matter candidate in supersymmetry. In the early universe, the flat directions of supersymmetry form scalar condensates with large expectation values. These condensates can subsequently fragment into non-topological solitons, SUSY Q-balls, which become the building blocks of PBHs. The PBH masses resulting from supersymmetry naturally fall into the sublunar mass window, where the PBHs can account for all dark matter. We will discuss two scenarios which result in the formation of PBHs. First, if the SUSY Q-balls dominate the energy density of the universe then statistical fluctuations and gravitational forces allow for the formation of PBHs in this intermediate matter-dominated era. Second, SUSY Q-balls may interact via a light scalar mediator. This attractive force allows for the formation of structure even in the radiation dominated era, while simultaneously removing energy and angular momentum from the systems of solitons by means of scalar radiation. These mechanisms are able to explain the present-day dark matter abundance in addition to potential candidate events observed with lensing experiments.
In the recent years, several measurements of $B$-decays with flavor changing neutral currents, i.e. $b\to s$ transitions hint at deviations from the Standard Model (SM) predictions. These decays are forbidden at tree-level in the SM and can only proceed via suppressed loop level or box diagrams. Rare decays of $B$ mesons are an ideal probe to search for phenomena beyond the SM, since contributions from new particles can affect the decays on the same level as SM particles.
The Belle II experiment is a substantial upgrade of the Belle detector and operates at the SuperKEKB energy-asymmetric $e^+ e^-$ collider. Radiative $b\to s \gamma$ decays is already been observed and inclusive photon spectra is also obtained with only a small dataset of Belle II. Early measurements related to the electro-weak penguin $b\to s \ell\ell$ and $b\to s \nu\bar\nu$ decays has also been performed. We will discuss the results obtained with the current dataset along with the prospects for the searches of these radiative and electroweak penguin decays with the expected $50~ab^{-1}$ full dataset of Belle II.
We study the supersymmetric (SUSY) effects on $C_7(\mu_b)$ and $C'_7(\mu_b)$
which are the Wilson coefficients (WC) for $b \to s \gamma$ at b quark
mass scale $\mu_b$ and are closely related to radiative B meson decays.
The SUSY-loop contributions to $C_7(\mu_b)$ and $C'_7(\mu_b)$ are calculated
at leading order (LO) in the Minimal Supersymmetric Standard Model (MSSM) with
general quark flavor violation (QFV). For the first time we perform a systematic
MSSM parameter scan for the WCs $C_7(\mu_b)$ and $C'_7(\mu_b)$ respecting all
the relevant constraints, i.e. the theoretical constraints from vacuum stability
conditions and the experimental constraints, such as those from $K$- and
$B$-meson data and electroweak precision data, as well as recent limits on SUSY
particle masses and the 125 GeV Higgs boson data from LHC experiments.
From the parameter scan, we find the following:
(1) The MSSM contribution to Re($C_7(\mu_b)$) can be as large as $\sim \pm 0.05$
which could correspond to about 3$\sigma$ significance of New Physics (NP)
signal in the future LHCb-Upgrade and Belle II experiments.
(2) The MSSM contribution to Re($C'_7(\mu_b)$) can be as large as $\sim -0.08$
which could correspond to about 4$\sigma$ significance of NP signal
in the future LHCb-Upgrade and Belle II experiments.
(3) These large MSSM contributions to the WCs are mainly
due to (i) large scharm-stop mixing and large scharm/stop involved
trilinear couplings $T_{U23}$, $T_{U32}$ and $T_{U33}$, (ii) large
sstrange-sbottom mixing and large sstrange-sbottom involved
trilinear couplings $T_{D23}$, $T_{D32}$ and $T_{D33}$ and
(iii) large bottom Yukawa coupling $Y_b$ for large $\tan\beta$
and large top Yukawa coupling $Y_t$.
In case such large NP contributions to the WCs are really observed
in the future experiments at Belle II and LHCb-Upgrade, this could
be the imprint of QFV SUSY (the MSSM with general QFV) and would
encourage to perform further studies of the WCs $C'_7(\mu_b)$ and
$C_7^{MSSM}(\mu_b)$ at higher order (NLO/NNLO) level in this model.
Note: This work is based on collaboration with Helmut Eberl, Elena Ginina
(HEPHY, Vienna) and Akimasa Ishikawa (Belle II, KEK).
Reference: arXiv:2106.15228 [hep-ph] (under submission to a journal)
Primordial gravitational waves (GWs) can be generated during different eras of early cosmic evolution, including inflation, cosmic phase transition, reheating/preheating, and so on. In this talk, I will first introduce the amplified GWs through parametric resonance during inflation in the Cherns-Simons gravity. Then, I will introduce the scalar induced GWs accompanied with the production of primordial black holes. Two different theoretical models how to enhance the curvature perturbations will be discussed.
Primordial black holes (PBHs) may form when the high peaks of the primordial density perturbation re-enter the Hubble horizon, while at the same time gravitational waves induced by the density perturbation at second order are generated. Currently observational constraints make it possible for asteroid-mass PBHs to be all dark matter, whose concomitant induced GWs are in the millihertz band. I will show that if all or a large portion of the PBHs are composed of dark matter, the corresponding induced gravitational wave energy spectrum must be detectable by space-borne interferometers like LISA, irrespective of linear local non-Gaussianity of the scalar perturbation.
I will report the current progress in our works on the detection of primordial black holes (PBHs) with gravitational waves, including the transients and the stochastic background of gravitational waves (SGWB). The observations of gravitational waves by LIGO open a new window to probe the PBHs, which could be a viable candidate of cold dark matter. We find that the scenario of PBHs can explain the merger rates of GW200105 and GW200115, which were claimed to be neutron star-black hole binaries. As a second observational window, SGWB can be also capable of constraining the abundance of PBHs through observations of SGWBs from the coalescing binaries and the enhanced curvature perturbations.
I describe the Sequestered Inflation as presented in the recent works with M. Gunaydin, A. Linde, Y. Yamada and T. Wrase in 2008.01494, 2108.08491, 2108.08492. We construct supergravity models allowing to sequester the phenomenology of inflation from the Planckian energy scale physics. The procedure consists of two steps: At Step I we study supergravity models associated with string theory or M-theory and find supersymmetric Minkowski vacua with flat directions. The corresponding massless Goldstone supermultiplets are related to the symmetries of flux superpotentials. At Step II we uplift these flat directions to inflationary plateau potentials using the nilpotent multiplet. The sequestered models include seven hyperbolic disks. Their predictions are among the main B-mode targets for future CMB experiments.
We describe the computation of the scattering amplitudes of massive spin-2 Kaluza-Klein excitations in a gravitational theory with a single compact extra dimension, whether flat or warped. These scattering amplitudes are characterized by intricate cancellations between different contributions: although individual contributions may grow as fast as O(s^5), the full results grow only as O(s). We demonstrate that the cancellations persist for all incoming and outgoing particle helicities and examine how truncating the computation to only include a finite number of intermediate states impacts the accuracy of the results. We also carefully assess the range of validity of the low energy effective Kaluza-Klein theory. In particular, for the warped case we demonstrate directly how an emergent low energy scale controls the size of the scattering amplitude, as conjectured by the AdS/CFT correspondence
Many extensions of the standard model predict new particles with long lifetimes or other properties, that give rise to non-conventional signatures in the detector. We present recent results of searches for new physics from such non-conventional signatures obtained using data recorded by the CMS experiment using the full Run-II LHC data-set.
A quirk propagating through a detector is subject to the Lorentz force, a new confining gauge force, and the frictional force from ionization energy loss. At the LHC, it was found that the monojet search and the coplanar search were able to constrain such a quirk signal. Inspired by the coplanar search proposed by S. Knapen et. al, we develop a new search that also utilizes the information of the relatively large ionization energy loss inside tracker. Our algorithm has improved efficiency in finding quirk signals with a wide oscillation amplitude. Because of our trigger strategy, the $Z(\to \nu\nu)+$jets process overlaid by pileup events is the dominant background. We find that the $\sim 100$ fb$^{-1}$ dataset at the LHC will be able to probe the colored fermion (scalar) quirks with masses up to {2.1 (1.1) TeV}, and the color neutral fermion (scalar) quirks with masses up to {450 (150) GeV}, respectively.
We explore the direct Higgs-top CP structure via the $pp \to t\bar{t}h$ channel with machine learning techniques, considering the clean $h \to \gamma\gamma$ final state at the high luminosity LHC~(HL-LHC). We show that a combination of a comprehensive set of observables, that include the $t\bar{t}$ spin-correlations, with mass minimization strategies to reconstruct the $t\bar{t}$ rest frame provide large CP-sensitivity.
We explain how the landscape can make predictions for Higgs and sparticle masses.
A power-law draw to large soft terms coupled with the ABDS anthropic condition that he derived weak scale be within a factor of a few of our measured value leads to m(h)~125 GeV with sparticles above present LHC limits. The spectra that emerges is that of radiatively driven natural SUSY. We show why such natural models are much more likely from the landscape than finetuned SUSY models.
We consider an explicit effective field theory example based on the Bousso-Polchinski framework with a large number N of hidden sectors contributing to supersymmetry breaking. Each contribution comes from four form quantized fluxes, multiplied by random couplings. The soft terms in the observable sector in this case become random variables, with mean values and standard deviations which are computable. We show that this setup naturally leads to a solution of the flavor problem in low-energy supersymmetry if N is sufficiently large. We investigate the consequences for flavor violating processes at low-energy and for dark matter.
String theory has no parameter except the string scale $M_S$, so the Planck scale $M_\text{Pl}$, the supersymmetry-breaking scale $m_{\rm susy}$, the electroweak scale $m_\text{EW}$ as well as the vacuum energy density (cosmological constant) $\Lambda$ are to be determined dynamically at any local minimum solution in the string theory landscape. Here we consider a model that links the supersymmetric electroweak phenomenology (bottom up) to the string theory motivated flux compactification approach (top down). In this model, supersymmetry is broken by a combination of the racetrack K\"ahler uplift mechanism, which naturally allows an exponentially small positive $\Lambda$ in a local minimum, and the anti-D3-brane in the KKLT scenario. In the absence of the Higgs doublets from the supersymmetric standard model, one has either a small $\Lambda$ or a big enough $m_{\rm susy}$, but not both. The introduction of the Higgs fields (with their soft terms) allows a small $\Lambda$ and a big enough $m_{\rm susy}$ simultaneously. Since an exponentially small $\Lambda$ is statistically preferred (as the properly normalized probability distribution $P(\Lambda)$ diverges at $\Lambda=0^{+}$), identifying the observed $\Lambda_{\rm obs}$ to the median value $\Lambda_{50\%}$ yields $m_{\text{EW}} \sim 100$ GeV. We also find that the warped anti-D3-brane tension has a SUSY-breaking scale $M_{\rm susy}\sim 100 \, m_{\text{EW}}$ while the SUSY-breaking scale that directly correlates with the Higgs fields in the visible sector is $m_{\rm susy} \simeq m_{\text{EW}}$.
The observation of 236 MeV muon neutrinos from kaon-decay-at-rest (KDAR) originating in the core of the Sun would provide a unique signature of dark matter annihilation. Since excellent angle and energy reconstruction are necessary to detect this monoenergetic, directional neutrino flux, DUNE with its vast volume and reconstruction capabilities, is a promising candidate for a KDAR neutrino search. In this talk, we evaluate the proposed KDAR neutrino search strategies by realistically modeling both neutrino-nucleus interactions and the response of DUNE. We find that, although reconstruction of the neutrino energy and direction is difficult with current techniques in the relevant energy range, the superb energy resolution, angular resolution, and particle identification offered by DUNE can still permit great signal/background discrimination. Moreover, there are non-standard scenarios in which searches at DUNE for KDAR in the Sun can probe dark matter interactions.
If the dark matter annihilation cross-section is velocity-dependent, then gamma-ray signals from astrophysical targets depend non-trivially on the dark matter velocity distribution. Since different targets can have different characteristic velocity scales, analyses of ensembles of targets can potentially find evidence for particular scenarios of dark matter microphysics. We discuss recent work on the prospects for future observations of dwarf spheroidal galaxies and galactic subhalos to not only detect evidence of dark matter annihilation, but also to determine the velocity dependence.
Extensive searches to probe the particle nature of dark matter (DM) have been going on for some decades now but, so far, no conclusive evidence has been found. Among various options, the Weakly Interacting Massive Particles (WIMP) remains one of the prime
possibilities as candidates for DM near the TeV scale. Taking a phenomenological view, such null results may be explained for a generic WIMP in a Higgs-portal scenario if we allow the light-quark Yukawa couplings to assume non-Standard Model (non-SM)-like values. This follows from a cancellation among different terms in the DM-nucleon scattering which can, in turn, lead to a vanishingly small direct-detection cross section. It might also lead to isospin violation in the DM-nucleon scattering. Such non-SM values of light-quark Yukawa couplings may be probed in the high luminosity run of the LHC.
We revisit the Higgs-invisible decay branching ratio in Higgs-portal dark matter models.
If the mass of the dark matter is slightly below the half of the mass of the Higgs boson, then pairs of the DM particles annihilate into the SM particles efficiently thanks to the Higgs resonance. The DM-Higgs coupling is required to be small to obtain the right amount of the dark matter relic abundance. As a result, the DM-nucleon scattering is highly suppressed and can explain the current null result of the dark matter signal at the direct detection experiments such as the XENON1T experiment. Another consequence of the tiny coupling is that the kinetic decoupling of dark matter from the thermal plasma in the early Universe may happen earlier. This implies that the standard calculation of the relic abundance may not be justified. We reevaluate the DM relic abundance with the evolution of the DM temperature. We show that the DM-Higgs coupling was underestimated in the literatures. Therefore, the Higgs invisible decay branching ratio is larger than previously expected, and the future collider experiments, such as the ILC experiment, can probe larger parameter space.
We study observable signals from dark matter that self-annihilates via Sommerfeld effect in dwarf spheroidal galaxies (dSphs). Since the effect of the Sommerfeld enhancement depends on the velocity of dark matter, it is crucial to determine the profile of dSphs to compute the J-factor, i.e., the line-of-sight integral of density squared. In our study we use the prior distributions of the parameters for satellite density profiles in order to determine the J-factor, making most out of the recent developments in the N-body simulations and semi-analytical modeling for the structure formation. As concrete model, we analyze fermionic dark matter that annihilates via a light scalar and Wino dark matter in supersymmetric models. We find that, with the more realistic prior distributions that we adopt in this study, the J-factor of the most promising dwarf galaxies is decreased by a factor of a few, compared with earlier estimates based on non-informative priors. Nevertheless, the Cherenkov Telescope Array should be able to detect thermal Wino dark matter by pointing it toward best classical or ultrafaint dwarf galaxies for 500 hours.
We revisit the scalar singlet dark matter (DM) accompanied by vectorlike dark leptons in two scenarios: in case I, the dark sector consists of a Dirac fermionic doublet; while in case II, a doublet fermion and a singlet. In both cases, the dark leptons couple with other dark sector particles and the Standard Model (SM) via gauge and Yukawa interactions. As a result, (i) new DM annihilation processes, including pair annihilation and coannihilation channels emerge, and (ii) new production channels for leptonic final states giving much enhancement in cross sections open up for DM searches in the LHC. In the former case, the mass splitting between the dark leptons is loop induced at best makes the distinction of the dark sector particles of different isospins a challenging task.
In the latter case, we alleviate the said limitation by introducing an extra singlet leptonic dark sector field. The "singlet-doublet mixing" produces an arbitrary mass splitting between the two components of the doublet in a gauge-invariant way, as well as provides a useful handle to distinguish between the dark sector particles of different isospins. As the dark leptons coannihilate non-trivially, the mixing effectively enhances the viable parameter space for the relic density constraint. In a low DM mass regime, with a non-zero mixing, it is possible to relax the existing indirect search bounds on the upper limit of the DM-SM coupling. From the analysis of the $3\tau + E_T^\mathrm{miss}$ and $\ell\tau + E_T^\mathrm{miss}$ channels for LHC at $\sqrt{s} = 13$ TeV, one ensures the presence of the mixing parameter between the dark sector particles of the theory by looking at the distinct peak and tail positions of the kinematic distributions, which remains a constant feature of the model. While both the channels present us the opportunity to detect the mixing signature at the LHC/HL-LHC, the former gives better results in terms of a larger region of mixing parameter. From the fiducial cross section, the projected statistical significance for the integrated luminosity, $\mathcal{L} = 3 ab^{-1}$, are shown for a combined parameter region obeying all the existing constraints, where there is the best possibility to detect such a signature.
The properties of primordial curvature perturbations on small scales are still unknown while those on large scales have been well probed by the observations of the cosmic microwave background anisotropies and the large scale structure. We propose the reconstruction method of primordial curvature perturbations on small scales through the merger rate of binary primordial black holes, which could form from large primordial curvature perturbation on small scales.
The axion objects such as axion mini-clusters and axion clouds around spinning black holes induce parametric resonances of electromagnetic waves through the axion-photon interaction. In particular, it has been known that the resonances from the axion with the mass around mueV may explain the observed fast radio bursts (FRBs). Here we argue that similar bursts of high frequency gravitational waves, which we call the fast gravitational wave bursts (FGBs), are generated from axion clumps with the presence of gravitational Chern-Simons (CS) coupling. The typical frequency is half of the axion mass, which in general can range from kHz to GHz. We also discuss the secondary gravitational wave production associated with FRB, as well as the possible host objects of the axion clouds, such as primordial black holes. Future detections of FGBs together with the observed FRBs are expected to provide more evidence for the axion.
Pulsar timing arrays record the arrival time of radio pulses from dozens of millisecond pulsars. The pulsars of different sky locations construct a network that is sensitive to gravitational waves and dark matter signals. There are three Pulsar timing arrays in the world, PPTA, EPTA and NANOGrav, that are actively gathering pulsar timing data with very high precision. In this talk, we use the recent PPTA data to search for ultralight dark photon dark matter signal and the phase transition gravitational wave background signal. We find that in both cases, the sensitivity of the current PPTA data exceeds the current limit in the low-frequency range, and a fair amount of parameter space can therefore be probed.
Binary extreme-mass-ratio inspiral (b-EMRIs) consists of a stellar-mass binary black hole orbiting around a supermassive massive black hole. Such a three-body system emits simultaneously low-frequency (milli-Hertz) gravitational waves and high-frequency (hundred Hertz) ones. Therefore, it is ideal for testing the dispersion of gravitational waves. In this talk, I will show how such systems could be produced naturally in astrophysical environments, via the processes of either tidal capture or planetary-like migration. By coordinating ground-based and future space-borne gravitational-wave observatories, we could constrain the dispersion of gravitational waves, and hence the mass of gravitons, to a precision that is ten times better than the current limit.
After the discovery of Higgs boson and gravitational wave (GW), the phase transition GW becomes a new and realistic approach to explore new physics and the fundamental physics. However, current predictions on the phase transition GW have large uncertainties from energy budget, bubble
wall velocity and so on. We study how to obtain more precise phase transitional GW
In the era of gravitational wave astronomy/cosmology, it is important not only to improve the sensitivity of existing detectors but also to extend detectable frequency range with novel methods. We show that gravitational waves can induce resonant spin precessions of electrons (magnon) in the presence of an external magnetic field. This phenomenon, we call it graviton-magnon resonance, enables us to probe gravitational waves in the GHz frequency range. Furthermore, we give upper limits on GHz gravitational waves by utilizing measurements of resonance fluorescence of magnons.
In this talk I review recent work on constructing a Penrose limit for the warped type IIB $AdS_6\times S^2\times \Sigma_2$ solutions and determining the spectrum of the Green-Schwarz string in the background.
In this talk I will start with a brief introduction of N=4 supergravity and the known results about the anomalies and divergences of N=4 supergravity in the literature. From there I will motivate the necessity for studying N=4 supergravity from the superconformal approach and discuss a systematic way to construct N=4 conformal supergravity. Then I will discuss how to use the superconformal results in the construction of N=4 Poincare supergravity with higher derivative corrections which would be relevant from the point of view of the above mentioned study of anomalies and divergences in N=4 supergravity. I will end with some future directions.
In several searches for additional Higgs bosons at the LHC,
in particular the CMS search in the·
$pp \to \phi \to t \bar t$ channel and the ATLAS search in·
the $pp \to \phi \to \tau^+\tau^-$
channel, a local excess at
the level of $3\,\sigma$ or above has been observed·
at a mass scale of $m_\phi \approx 400$GeV.·
We investigate to what extent a possible signal in those
channels could be accommodated in the·
Next-to-Two-Higgs-Doublet Model (N2HDM) or the Next-to Minimal
Supersymmetric Standard Model (NMSSM).
In a second step we furthermore analyse
whether such a model could be compatible with both a signal at·
$\approx 400$GeV and at $\approx 96$GeV, where the latter possibility is
motivated by observed excesses in searches for the $b \bar b$ final state at·
LEP and the di-photon final state at CMS.
The analysis for the N2HDM reveals that the
observed excesses at $\approx 400$GeV in the
$pp \to \phi \to t \bar t$ and
$pp \to \phi \to \tau^+\tau^-$ channels point
towards different regions of the parameter space, while one such excess and an
additional Higgs boson at $\approx 96$GeV could simultaneously be
accommodated. In the context of the NMSSM·
an experimental confirmation of a signal in the·
$t \bar t$ final state would favour·
the alignment-without-decoupling limit of the model,
where the Higgs boson at $\approx 125$GeV could be essentially
indistinguishable from the Higgs boson of the SM.·
In contrast,·
a signal in the $\tau^+\tau^-$ channel would be correlated with significant
deviations of the properties of the Higgs boson at $\approx 125$GeV·
from the ones of a SM Higgs boson that could be detected with high-precision
coupling measurements.
We discuss a ∼ 3 σ signal (local) in the light Higgs-boson search in the diphoton decay mode at ∼ 96 GeV as reported by CMS, together with a ∼ 2 σ excess (local) in the b̄b final state at LEP in the same mass range. We interpret this possible signal as a Higgs boson in the 2 Higgs Doublet Model with an additional complex Higgs singlet (2HDMS). We find that the lightest CP-even Higgs boson of the 2HDMS type II can perfectly fit both excesses simultaneously, while the second lightest state is in full agreement with the Higgs-boson measurements at 125 GeV, and the full Higgs-boson sector is in agreement with all Higgs exclusion bounds from LEP, the Tevatron and the LHC as well as other theoretical and experimental constraints. We derive bounds on the 2HDMS Higgs sector from a fit to both excesses and describe how this signal can be further analyzed at the LHC and at future e⁺e⁻ colliders, such as the ILC or CEPC. We analyze in detail the anticipated precision of the coupling measurements of the 96 GeV Higgs boson at the ILC.
The presence of charged Higgs bosons is a generic prediction of multiplet extensions of the Standard Model (SM) Higgs sector. Focusing on the Two-Higgs-Doublet-Model (2HDM), we discuss the charged Higgs boson collider phenomenology in the theoretically and experimentally viable parameter space. While almost all existing experimental searches at the LHC target the fermionic decays of charged Higgs bosons, we point out that the bosonic decay channels --- especially the decay into a non-SM-like Higgs boson and a W boson --- often dominate over the fermionic channels. We propose several benchmark scenarios with distinct phenomenological features in order to facilitate the design of dedicated LHC searches for charged Higgs bosons decaying into a W boson and a non-SM-like Higgs boson.
We explore the possibility of displaced Higgs production from the decays of the heavy fermions in the Type-III seesaw extension of the Standard Model at the LHC/FCC and the muon collider. The displaced heavy fermions and the Higgs boson can be traced back by measuring the displaced charged tracks of the charged leptons along with the $b$-jets. The prospects of the transverse and longitudinal displaced decay lengths are extensively studied in the context of the boost at the LHC/FCC. Due to the parton distribution function, the longitudinal boosts leads to larger displacement compared to the transverse one, which can reach MATHUSLA and beyond. Such measurements are indeed possible by the fully visible finalstate, which captures the complete information about the longitudinal momenta. The comparative studies are made at the LHC/FCC with the centreof mass energies of 14, 27 and 100 TeV, respectively. . A futuristic study of the muon colliderwhere the collision happen in the centre of mass frame is analysed for centre of mass energiesof 3.5, 14 and 30 TeV. Contrary to LHC/FCC, here the transverse momentum diverges,however, the maximum reach in both the direction are identical due to the constant total momentum in each collision. The reach of the Yukawa couplings and fermion masses areappraised for both the colliders.
We present a summary of searches for new heavy resonances decaying into pairs or triplets of bosons, performed on proton-proton collision data collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV. A common feature of these analyses is the boosted topology, namely the decay products of the considered bosons (both electroweak W, Z bosons and the Higgs boson) are expected to be highly energetic and close in angle, leading to a non-trivial identification of the quarks and leptons in the final state. The exploitation of jet substructure techniques allows to increase the sensitivity of the searches where at least one boson decays hadronically. Various background estimation techniques are adopted, based on data-MC hybrid approaches or relying only in control regions in data. Results are interpreted in the context of multiple scenarios beyond the standard model.
In this talk, I will present the phenomenology of dark-matter production in the case where it is both produced by a freeze-out or freeze-in mechanism and by the evaporation of primordial black holes. I will show that the presence of a vector mediator between the hidden and the visible sector affects the production of dark-matter particles as well as its phase space distribution. I will also show that the population of DM particles produced by evaporation may be warm enough to re-thermalize with the pre-existing DM relic abundance, leading to non-trivial imprints on the value of the relic abundance at later time.
A fraction of the dark matter in the solar neighborhood might be composed of non-galactic particles with speeds larger than the escape velocity of the Milky Way. The non-galactic dark matter flux would enhance the sensitivity of direct detection experiments, due to the larger momentum transfer to the target. In this note, we calculate the impact of the dark matter flux from the Local Group and the Virgo Supercluster diffuse components in nuclear and electron recoil experiments. The enhancement in the signal rate can be very significant, especially for experiments searching for dark matter induced electron recoils.
The Belle II experiment at the asymmetric $e^+e^-$ collider, SuperKEKB, is a substantial upgrade of the Belle/KEKB experiment. Belle II aims to record 50 ab$^{-1}$ of data over the course of the project. During the first physics runs in 2018-2020, around 100 fb$^{-1}$ of data were collected. These early data include specifically-designed low-multiplicity triggers which allow a variety of searches for light dark matter and dark-sector mediators in the GeV mass range.
This talk will present the very first world-leading physics results from Belle II: searches for the invisible decays of a new vector Z’, and visible decays of an axion-like particle; as well as the near-term prospects for other dark-sector searches. Many of these searches are competitive with the data already collected or the data expected in the next few years of operation.
The non-observation of conclusive WIMP signals raises the question whether WIMPs can still account for the dark matter of the universe. In this talk I will present results from a global analysis of effective field theory operators describing the interactions between WIMPs and Standard Model particles. In this bottom-up approach, the global fitting framework GAMBIT is used to simultaneously vary the coefficients of 14 such operators, along with the WIMP mass, the scale of new physics and several nuisance parameters. The likelihood functions include the latest data from Planck, direct and indirect detection experiments, and the LHC. Although the observed relic density can be reproduced in large regions of parameter space, there cannot be a large hierarchy between the WIMP mass and the scale of new physics, which raises concerns about the validity of the effective field theory. I will discuss possible ways to address this issue in order to consistently interpret the latest results from WIMP searches at the LHC.
Feebly Interacting Massive Particles (FIMPs) are dark matter candidates that never thermalize in the early universe and whose production takes place via decays and/or scatterings of thermal bath particles. If FIMPs interactions with the thermal bath are renormalizable, a scenario which is known as freeze-in, production is most efficient at temperatures around the mass of the bath particles and insensitive to unknown physics at high temperatures. Working in a model-independent fashion, we consider three different production mechanisms: two-body decays, three-body decays, and binary collisions. We compute the FIMP phase space distribution and matter power spectrum, and we investigate the suppression of cosmological structures at small scales. Our results are lower bounds on the FIMP mass. Finally, we study how to relax these constraints in scenarios where FIMPs provide a sub-dominant dark matter component.
Extensions of the two higgs doublet models with a singlet scalar can easily accommodate all current experi-
mental constraints and are highly motivated candidates for Beyond Standard Model Physics. It can success-
fully provide a dark matter candidate, explain baryogenesis and provide gravitational wave signals. In this
work, we focus on the dark matter phenomenology of the two higgs doublet model extended with a complex
scalar singlet which serves as the dark matter candidate. We study the variations of the dark matter observ-
ables, i.e relic density and direct detection cross-section, with respect to the model parameters. We obtain a
few benchmark points in the light and heavy dark matter mass region. We are also currently studying possi-
ble signatures of this model at current and future colliders and the possibility to distinguish this model from
other new physics scenarios.
We discuss phenomenological viability of a novel inflationary model in the minimal gauge mediated supersymmetry breaking scenario. In this model, cosmic inflation is realized in the flat direction along the messenger supermultiplets and a natural dark matter candidate is the gravitino from the out-of-equilibrium decay of the bino-like neutralino at late times, which is called the superWIMP scenario. The produced gravitino is warmish and can have a large free-streaming length; thus the cusp anomaly in the small scale structure formation may be mitigated. We show that the requirement of the Standard Model Higgs boson mass to be $m_{h^0}=125.1$ GeV gives a relation between the spectrum of the cosmic microwave background and the messenger mass $M$. We find, for the e-folding number $N_e=60$, the Planck 2018 constraints (TT, TE, EE+lowE+lensing+BK15+BAO, 68% confidence level) give $M > 3.64\times 10^7$ GeV. The gravitino dark matter mass is $m_{3/2} < 5.8$ GeV and the supersymmetry breaking scale $\Lambda$ is found to be in the range $(1.28-1.33)\times 10^6$ GeV. Future CMB observation is expected to give tighter constraints on these parameters.
A $t$-channel singularity of a cross section occurs in a $2\to 2$ process when the mediator is allowed to be on-shell, i.e. when the process can be treated as a sequence of a $1\to 2$ decay and a $2\to 1$ inverse decay. If, moreover, the mediator is stable, this singularity cannot be regularized within the common Breit-Wigner approach.
In this talk I will discuss the conditions for the singularity to occur and briefly summarize attempts (proposed in literature) to regularize it in case of collider physics and cosmological considerations of a thermal medium of particles. After showing that none of previously proposed ways to solve the problem is satisfactory in the cosmological case, I will present a natural solution developed within the Keldysch-Schwinger formalism: a non-zero imaginary part of the mediator's self-energy that appears as a consequence of interactions between the mediator and the thermal medium. Consequently, the mediator acquires a non-zero effective decay width and the cross section becomes finite.
We discuss the preinflationary dynamics of the spatially flat FLRW universe filled with a single scalar field that has the generic potentials, in the framework of loop quantum cosmology. The evolution can be divided into two different classes, one is dominated initially (at the quantum bounce) by the kinetic energy of the scalar field, and one is not. In both cases, we identify numerically the physically viable initial conditions that lead to not only a slow-roll inflationary phase, but also enough e-folds to be consistent with observations, and find that the output of such a viable slow-roll inflationary phase is generic. In addition, we also show that in the case when the evolution of the universe is dominated initially by the kinetic energy of the scalar field, the evolution before reheating is always divided into three different phases: bouncing, transition and slow-roll inflation.
The Gravity effects play an important role both in the black hole scattering and early universe inflation. On the other hand, extremely heavy dynamic systems, e.x. The black hole and early universe, provide a natural environment for detecting classical and quantum gravitational effects. In this talk, we majorly focus on the theoretical part of the gravity effects. We propose a systematic framework to obtain the classical and quantum gravity effect on the two-body scattering bending angle. The framework is based on the heavy-mass effective field theory approach to general relativity. The amplitudes in this effective field theory are constructed using a recently proposed novel color-kinematic/double copy duality, where the duality numerators are gauge invariant and local concerning the massless gravitons. We provide the explicit result on two body bending angles to the third post-Minkowskian order for the classical part and the one-loop order for the quantum part.
After motivating gravity and cosmology beyond general relativity, I will review some theories and their phenomenologies, inclucing gravitational wave physics.
Lorentz symmetry is the cornerstone of modern physics, and is consistent with all experiments carried out so far. However, due to various motivations, gravitational theories with Lorentz symmetry breaking have been proposed, and one of the examples is the Horava-Lifshitz theory, motivated by the quantization of gravity. Another example is the Einstein-aether (æ-) theory, which is a vector-tensor theory with the vector (aether) field being always timelike and unity. The æ-theory is self-consistent (such as free of ghosts and instability), and satisfies all the experimental tests carried out so far. Its Cauchy problem is well-posed, and energy is always positive (at least as far as the hypersurface-orthogonal aether field is concerned). In addition, black holes exist and can be formed from gravitational collapse of realistic matter.
In this talk, we shall present our recent studies of gravitational waves (GWs) produced by massive and compact objects in æ-theory, including their waveforms, polarizations, response function, its Fourier transform, and energy loss rate through three different channels of radiation, the scalar, vector and tensor modes. Combination of such theoretical predictions with observations of GWs can bring severe constraints on the theory.
The orbital period loss of Hulse-Taylor binary system was the first indirect evidence of gravitational wave (GW) which confirms Einstein's general theory of relativity to a very good extent. However the uncertainty in the measurement of GW from observation and GR prediction allows us to probe physics beyond the standard picture. In this talk I will discuss about probing beyond standard model physics from GW observation and some other astrophysical phenomena.
A fast-spinning axion can dominate the Universe at early times and generates the so-called kination era. The presence of kination imprints a smoking-gun spectral enhancement in the primordial gravitational-wave (GW) background. Current and future-planned GW observatories could constrain particle theories that generate the kination phase. Surprisingly, the viable parameter space allows for a kination era at the PeV-EeV scale and generates a peaked spectrum of GW from either cosmic strings or primordial inflation, which lies inside ET and CE windows.
There are strong interests in considering ultra-light scalar fields (especially axion) around a rapidly rotating black hole because of the possibility of observing gravitational waves from axion condensate (axion cloud) around black holes. Motivated by this consideration, we propose a new method to study the dynamics of an ultra-light scalar field with self-interaction around a rapidly rotating black hole, which uses the dynamical renormalization group method. We find that for relativistic clouds, a saturation of the superradiant instability by the scattering of the axion due to the self-interaction does not occur in the weakly non-linear regime when we consider the adiabatic growth of the cloud from a single superradiant mode. This may suggest that an explosive phenomenon called the Bosenova may inevitably happen for relativistic axion clouds, at least once in its evolutionary history.
We show that photon spheres of supermassive black holes generate high-frequency stochastic gravitational waves through
the photon-graviton conversion.
Remarkably, the frequency is universally determined as $m_e\sqrt{m_e /m_p} \simeq 10^{20} \text{Hz}$ in terms of the proton mass $m_p$ and the electron mass $m_e$.
It turns out that the density parameter of the stochastic gravitational waves $ \Omega_{ \text{gw}}$ could be $ 10^{-12}$.
Since the existence of the gravitational waves from photon spheres is robust,
it is worth seeking methods of detecting high-frequency gravitational waves around $10^{20}$Hz.
The landscape of supergravity theories arising from string compactifications is highly constrained by the internal geometry. In this talk, I will argue that, rather than being a limitation of string model building, these geometric constraints reflect physical consistency conditions that delineate the landscape from the swampland. I will focus on constructions of 8d and 6d supergravity theories via F-theory, and discuss geometric restrictions on the possible gauge symmetries, including the global structure of the gauge group. As I will explain in the talk, the corresponding physical consistency conditions are related to (generalized) global symmetries.
I will discuss recent progress in finding and classifying de Sitter vacua in supergravity. I will also comment on the evidence that models with de Sitter vacua with massless gravitini in the swampland.
The Circular Electron Positron Collider is designed to deliver 1 M Higgs boson, 100 M W boson, 1 Tera Z boson in roughly 10 years of data taking. It is not only a machine for precision measurement but also a Discovery machine. To quantify its physics potential and comparative advantages compared to other facilities, intensive physics studies have been performed, aiming at CEPC physics white papers in a few years.
This report will briefly introduce the status and highlights of recent CEPC physics studies.
The discovery of the Higgs boson marked the beginning of a new era in HEP. Precision measurement of the Higgs boson properties and exploring new physics beyond the Standard Model using Higgs as a tool become a natural next step beyond the LHC. Among the proposed Higgs factories worldwide, the Circular Electron Positron Collider (CEPC) is proposed by the Chinese HEP community and to be hosted in China. The CEPC will be located in a tunnel with 100km circumference. It will operate at CME of 240 GeV as a Higgs factory. It can also operate at lower energy as W and Z boson factory. In this talk, the recent progress about CEPC accelerator and detector R&D, and study of physics potential will be presented.
After the recent update of the European Strategy an International Muon Collider Collaboration is forming. The talk will give an overview of the project and the plans of the collaboration. It will highlight some of the challenges and the technologies to address them.
The talk will summarise the status of the muon collider physics potential assessment
Leptoquarks (LQ) are predicted by many new physics theories to describe the similarities between the lepton and quark sectors of the Standard Model and offer an attractive potential explanation for the lepton flavour anomalies observed at LHCb and flavour factories. The ATLAS experiment has a broad program of direct searches for leptoquarks, coupling to the first-, second- or third-generation particles. This talk will present the most recent 13 TeV results on the searches for leptoquarks and contact interactions with the ATLAS detector, covering flavour-diagonal and cross-generational final states.
We present an overview of searches for new physics with top and bottom quarks in the final state, using proton-proton collision data collected with the CMS detector at the CERN LHC at a center-of-mass energy of 13 TeV. The results cover non-SUSY based extensions of the SM, including heavy gauge bosons or excited third generation quarks. Decay channels to vector-like top partner quarks are also considered. We explore the use of jet substructure techniques to reconstruct highly boosted objects in events, enhancing the sensitivity of these searches
Missing transverse momentum (MET) is a critical observable for physics searches in proton-proton collisions at the Large Hadron Collider. This talk describes these various novel approaches and their performance. ATLAS employs a suite of working points for missing transverse momentum (MET) reconstruction, and each is optimal for different event topologies. A new neural network can exploit various event properties to pick the optimal working point on an event-by-event basis and also combine complementary information from each of the working points. The resulting regressed "METNet" offers improved resolution and pileup resistance across a number of different topologies compared to the current MET working points. Additionally, image-based de-noising neural network techniques are studied; these also provide significant resolution improvements and pileup resistance.
The Bell inequality is a principal touchstone of testing the local realism posited by Einstein at the time of the formation of quantum theory. The violations of the Bell inequality have been found with the measured system of photons, electrons or nucleons at low energies, which reject local realism. Extending to systems with higher energies will be important for establishing the nonlocal nature universally.
This talk will present a simulation study on the feasibility of the Bell test by means of flavor entanglement of a pair of B mesons in the ATLAS experiment at CERN. Our results show that it is capable to find the maximal violation of the Bell inequality at the time difference of 1.5 ps in the decays of the two entangled B mesons, rejecting yet again the local realism at the highest energy scale 14 TeV ever. This will be the first case of Bell inequality violation in particle physics experiment, given that the earlier analysis with the Belle experiment was found to be inconclusive, due primarily to the lack of selection process of spacelike events and the inability of independent identification of the decay times.
The reconstruction and calibration of hadronic final states is an extremely challenging experimental aspect of measurements and searches at the LHC. This talk summarizes the latest results from ATLAS for jet reconstruction and calibration. New approaches to jet inputs better utilize relationships between calorimeter and tracking information to significantly improve the reconstruction of jet substructure. Additionally, a full suite of in-situ measurements of the jet energy scale and jet energy resolution for ATLAS's new particle flow jets yield the lowest uncertainties yet in the high pileup conditions of the LHC Run 2. Finally, new machine learning approaches for various aspects of reconstruction will be discussed.
The minimal U$(1)_𝑋$ extension of the Standard Model (SM) is a simple and well-motivated extension of the SM, which supplements the SM with the seesaw mechanism for naturally generating the light neutrino masses and offers various interesting phenomenologies.In the model, the U$(1)_𝑋$ charge of each SM field is characterized by the U$(1)_𝑋$ charge of the SM Higgs doublet with a free parameter $x_𝐻$ and $𝑥_\Phi$. Due to the U$(1)_𝑋$ charge of the Higgs doublet, the Higgs boson has a trilinear coupling with the $𝑍$ and the U$(1)_𝑋$ gauge boson $(𝑍^\prime)$ due to $𝑥_𝐻 \neq 0$. With this coupling, a new process for the associated Higgs boson production with $𝑍$ boson arises through a $𝑍^\prime$ boson in the $𝑠$-channel at high energy colliders. In this paper, we calculate the associated Higgs boson production at high energy colliders and show the interesting effects of the new $𝑍^\prime$ boson mediated process, which can be tested in the future. Such models contains three SM singlet RHNs which generate the light neutrino mass through the seesaw mechanism after the U$(1)_𝑋$ breaking. We will also study the prospect of such RHN productions through the Higgs boson at the colliders which can probe a suitable neutrino mass generation mechanism.
Gauge coupling unification in the Supersymmetric Standard Models strongly implies the
Grand Unified Theories (GUTs). With the grand desert hypothesis, we show that
the supersymmetric GUTs can be probed at the future proton-proton (pp) colliders and
Hyper-Kamiokande experiment. For the GUTs with the GUT scale $M_{GUT} \le 1.0\times 10^{16}$~GeV,
we can probe the dimension-six proton decay via heavy gauge boson exchange
at the Hyper-Kamiokande experiment. Moreover, for the GUTs with
$M_{GUT} \ge 1.0\times 10^{16}$~GeV, we for the first time study the upper bounds
on the gaugino and sfermion masses. We show that the GUTs with anomaly and
gauge mediated supersymmetry breakings are well within the reaches of
the future 100 TeV pp colliders such as the ${\rm FCC}_{\rm hh}$ and SppC,
and the supersymmetric GUTs with gravity mediated supersymmetry breaking
can be probed at the future 160 TeV pp collider.
In high-scale supersymmetry where all sparticles, except gravitino, are heavier than inflaton, an EeV-scale gravitino is suited for dark matter. Gravitino may be produced not only from scatterings of thermal particles but also from radiative decay of inflaton even when there is no direct coupling between the two. I will argue that in a viable inflation model based on no-scale supergravity, the latter can be a non-negligible contribution.
What is the upper limit of the mass of the neutralino dark matter whose thermal relic is consistent with the observation? If the neutralino dark matter and colored sparticles are extremely degenerated in mass, with a mass difference less than the QCD scale, the dark matter annihilation is significantly increased and enjoys the "second freeze-out" after the QCD phase transition. In this case, the neutralino dark matter with a mass much greater than 100 TeV can realize the correct dark matter abundance. We study the dark matter abundance and its detection in the case of such highly degenerated mass spectrum of the neutralino dark matter and colored supersymmetric particles.
We explore a missing-partner model based on the minimal SU(5) gauge group with 75, 50 and 50 Higgs representations, assuming a super-GUT CMSSM scenario in which soft supersymmetry-breaking parameters are universal at some high scale above the GUT scale. We identify regions of parameter space that are consistent with the cosmological dark matter density, the measured Higgs mass and the experimental lower limit on proton lifetime. These constraints can be satisfied simultaneously along stop coannihilation strips. We find that the lifetime of the proton decay into K+ and neutrino is less than 3 x 10^{34} years throughout the allowed range of parameter space, within the range of the next generation of searches with the JUNO, DUNE and Hyper-Kamiokande experiments.
We perform an analysis of the vacuum stability of the neutral scalar potential of the $\mu$-from-$\nu$ Supersymmetric Standard Model ($\mu\nu$SSM). As an example scenario, we discuss the alignment without decoupling limit of the $\mu\nu$SSM. We demonstrate that in this limit large parts of the parameter space feature unphysical minima that are deeper than the electroweak minimum. In order to estimate the lifetime of the electroweak vacuum, we calculate the decay rates for the tunneling process into each unphysical minimum. We find that in many cases the resulting lifetime is longer than the age of the universe, such that the considered parameter region is not excluded. On the other hand, we also find parameter regions in which the EW vacuum is short-lived, and we demonstrate how these regions are related to the presence of light right-handed sneutrinos.
Based on 3 papers: arXiv:2002.05554, 2003.01662, 2011.12848
1.“A Novel Scenario in the Semi-constrained NMSSM,” JHEP 06, 078 (2020)
2.“Funnel annihilations of light dark matter and the invisible decay of the Higgs boson,”Phys. Rev. D 101, no.9, 095028 (2020)
3. “Higgsino Asymmetry and Direct-Detection Constraints of Light Dark Matter in the NMSSM with Non-Universal Higgs Masses,” Chin. Phys. C 45, no. 4, 041003 (2021)
The fully constrained NMSSM is in tension with current experimental constraints. Therefore, we focuses on a simple and elegant supersymmetric model: semi-constrained NMSSM (scNMSSM).
In order to better explore the parameter space of scNMSSM, we have developed a new search algorithm: the Heuristically Search (HS) and the Generative Adversarial Network (GAN).
We applied this very effective search algorithm to the parameter space of scNMSSM. For the first time (according to the current understanding), we successfully found a parameter space that satisfies all the theoretical and experimental constraints, and then we made analysis of the Higgs and dark matter properties.
We carefully studied the Higgs and dark matter LSP scenario in the scNMSSM. We found that in scNMSSM, there can be four funnel-annihilation mechanisms for the LSP in scNMSSM, which are the $h_2$, $Z$, $h_1$ and $a_1$ funnel. We also verified that the spin-dependent cross section is proportional to the square of higgsino asymmetry. And the higgsino-mass parameter $\mu$ is smaller than about $335 $ GeV in the scNMSSM due to the current muon g-2 constraint.
We will consider the proton decay in a class of minimal SU(5) GUTs mediated by color-triplets Higgsinos. Even though their masses are comparable with the GUT scale, they can still yield a shorter lifetime for the proton, especially in the low tan beta region. In this work, we consider several threshold effects from Planck-suppressed operators, which lead to heavier triplet Higgsinos as well as correcting the wrong fermion mass relations realized in SU(5) GUTs.
Results from the CMS experiment are presented for searches for strong supersymmetric with decays to hadronic final states. The searches use proton-proton collision data with luminosity up to 137 fb-1 recorded by the CMS detector at center of mass energy 13 TeV during the LHC Run 2.
Despite the absence of experimental evidence, weak-scale supersymmetry remains one of the best motivated and studied Standard Model extensions. This talk summarizes recent ATLAS results on inclusive searches for supersymmetric squarks of the first two generations and gluinos, focusing on decay modes in which R-parity is conserved and therefore the lightest SUSY particle is a stable dark matter candidate. The searches target final states including jets, leptons, photons, and missing transverse momentum.
In this talk I will discuss the case of a light LSP (lighter than half the Higgs mass) in pMSSM, NMSSM as well as both these models extended with a right handed sneutrino. In addition I will point out some new strategies for heavy higgs searches in electroweakino final states as well as remind us of the importance of the precision calculations in the Higgs sector for the phenomenology.
I shall review the motivations for grand unification and summarize recent progress in this field.
I describe a reanalysis of data sets that have previously been found to harbor evidence for an unidentified X-ray line at 3.5 keV in order to quantify the robustness of earlier results that found significant evidence for a new X-ray line at this energy. The 3.5 keV line is intriguing in part because of possible connections to dark matter. We analyze observations from the XMM-Newton and Chandra telescopes. We investigate the robustness of the evidence for the 3.5 keV line to variations in the analysis framework and also to numerical error in the chi-square minimization process. For example, we consider narrowing the energy band for the analysis in order to minimize mismodeling effects. The results of our analyses indicate that many of the original 3.5 keV studies (i) did not have fully converged statistical analyses, and (ii) were subject to large systematic uncertainties from background mismodeling. Accounting for these issues we find no statistically significant evidence for a 3.5 keV line in any X-ray data set.
The search for dark matter (DM) weakly interacting massive particles with noble elements has probed masses down and below a GeV/c^2. The ultimate limit is represented by the experimental threshold on the energy transfer to the nuclear recoil. Currently, the experimental sensitivity has reached a threshold equivalent to a few ionization electrons. In these conditions, the contribution of a Bremsstrahlung photon or a so-called Migdal electron due to the sudden acceleration of a nucleus after a collision might be sizeable. We present a recent work where, using a Bayesian approach, we studied how these effects can be exploited in experiments based on liquid argon detectors. In particular we develop a simulated experiment to show how the Migdal electron and the Bremsstrahlung photon allow to push the experimental sensitivity down to masses of 0.1 GeV/c^2, extending the search region for dark matter particles of previous results. For these masses we estimate the effect of the Earth shielding that, for strongly interacting dark matter, makes any detector blind. Finally, given the relevance of the Migdal electrons to the search for low mass DM, we discuss some new ideas on how to possibly measure such an effect with detectors based on a Time Projection Chamber exposed to an high neutron flux.
Abstract: A large amount of data from dwarf galaxies to galaxy clusters appears to indicate that dark matter (DM) acts like a collisional fluid at galaxy scales to a collisionless fluid at the scale of galaxy clusters. We will discuss a particle physics model with the standard model extended with a gauged abelian hidden sector to explain this phenomenon. In this model dark matter consists of fermions of the hidden sector and they have self interactions via exchange of dark photons which constitute
a new dark force in the model. The analysis involves solutions to Boltzmann equations coupling the visible sector and the hidden sectors at different temperatures, one for each sector. The model produces a velocity - dependent DM cross section where the DM acts like a collisional fluid at small galaxy scales and acts collisionless at large galaxy scales, and we fit the data including those from THINGS, LSB and the Bullet Cluster. The talk is based on the paper Phys. Rev. D 103, 075014 (2021), arXiv: 2008.00529 [hep-ph], by Amin Aboubrahim, Wan-Zhe Feng, Pran Nath, and Zhu-Yao Wang.
I argue that generic features of string compactifications, namely a high scale of supersymmetry breaking and one or more epochs of modulus domination, can accommodate superheavy neutralino dark matter with a mass around 10^10−10^11 GeV. Interestingly, this mass range may also explain the recent detection of ultra-high-energy neutrinos by IceCube and ANITA via dark matter decay.
A scheme of simplified smooth hybrid inflation is realized in the framework of supersymmetric $SU(5)$. The smooth model of hybrid inflation provides a natural solution to the monopole problem that appears in the breaking of $SU(5)$ gauge symmetry. The supergravity corrections with nonminimal Kahler potential are shown to play important role in realizing inflation with a red-tilted scalar spectral index $n_s <1$, within Planck's latest bounds. As compared to shifted model of hybrid inflation, relatively large values of the tensor-to-scalar ratio $r \leq 0.01$ are achieved here, with nonminimal couplings $-0.05 \leq \kappa_S \leq 0.01$ and $-1 \leq \kappa_{SS} \leq 1$ and the gauge symmetry-breaking scale $M \simeq (2.0 - 16.7) \times 10^{16}$ GeV.
The axion is a well-motivated candidate for the inflaton, as the radiative corrections that spoil many single-field models are avoided by virtue of its shift symmetry. However, axions generically couple to gauge sectors. As the axion rolls through its potential, this coupling can result in the production of a co-evolving thermal bath, a situation known as "warm inflation." Inflationary dynamics in this warm regime can be dramatically altered and result in significantly different observable predictions. In this talk, I will show that for large regions of parameter space, axion models once assumed to be safely "cold" are in fact warm, and must be reevaluated in this context.
Supersymmetric flat directions develop large expectation values in the early universe, leading to formation of SUSY Q-balls and ultimately primordial black holes (PBH). This makes PBHs a natural and generic dark matter candidate in supersymmetry. The PBH masses resulting from supersymmetry naturally fall into the sublunar mass window, where the PBHs can account for all dark matter. We will discuss two scenarios which result in the formation of PBHs. First, if the SUSY Q-balls dominate the energy density of the universe then statistical fluctuations and gravitational forces allow for the formation of PBHs in this intermediate matter-dominated era. Second, SUSY Q-balls may interact via a light scalar mediator. This attractive force allows for the formation of structure even in the radiation dominated era, while simultaneously removing energy and angular momentum from the systems of solitons by means of scalar radiation. These mechanisms are able to explain the present-day dark matter abundance in addition to potential candidate events observed with lensing experiments.
Fermilab has just announced a new experimental result for muon g-2. The statistical uncertainty of the new result is similar to the previous BNL result and the central value is consistent. The combined value is now 4.2 standard deviation away from the Standard Model prediction. For the Standard Model prediction, the two hadronic contributions, HVP (hadronic vacuum polarization) and HLbL (hadronic light-by-light) are the dominate sources of uncertainty. I will review the lattice calculations in determining these two hadronic contributions.
Hadronic vacuum polarization is a key ingredient of the SM prediction for g-2. However, it also enters the global EW fit, linking both of them. In this talk I discuss this interplay as well as the possible presence of NP in the EW fit and g-2.
I will argue that the slope of the spectrum of
gravitational waves may provide us evidence of
superstring effects in early universe cosmology. Both
String Gas Cosmology and the S-Brane Mediated Ekpyrotic
scenario predict a blue tilt of the tensor spectrum.
We discuss the footprint of evaporation of primordial black holes (PBHs) on stochastic gravitational waves(GWs) induced by scalar perturbations. We consider the case where PBHs once dominated the Universe but eventually evaporated before the big bang nucleosynthesis. The reheating through the PBH evaporation could end with a sudden change in the equation of state of the Universe compared to the conventional reheating caused by particle decay. We show that this “sudden reheating” by the PBH evaporation enhances the induced GWs, whose amount depends on the length of the PBH-dominated era and the width of the PBH mass function. We also explore the possibility to constrain the primordial abundance of the evaporating PBHs by observing the induced GWs. This presentation will be based on our paper, arXiv:2003.10455.
I will describe the construction of a curious 4-derivative extension of 6D, N=(1,0) supergravity coupled to hypermultiplets whose scalar fields parametrize a quaternionic projective space. Surprisingly, we find that the inclusion of the Riemann-squared term is not allowed. Dimensional reduction of Bergshoeff-de Roo heterotic supergravity with Riemann-squared terms, on the other hand, suggests that such an inclusion should be possible if the scalars parametrize a Grassmannian coset. To compare the two cases, I will describe the dimensional reduction of BdR supergravity on 4-torus followed by a consistent truncation to (1,0) supersymmetry. In this case, we can see that the Riemann-squared term and 4-derivative scalar field couplings co-exist, but we also encounter an obstacle due to presence of certain terms in the fermionic sector that break the expected SO(4)xSO(4) composite local symmetry down to its diagonal SO(4) subgroup.
I will present a novel solution to the long-standing issue of obtaining de Sitter spacetimes from a pure Supergravity theory. Our model is based on the first superspace formulation of unimodular gravity, in conjunction with a (super)-Stueckelberg construction. I will then present a comparison between our model and other proposals in the literature, based on constrained superfields. Even through the approaches are very different, I will show that the two proposals converge towards the same theory, thus offering a tantalising glimpse of a more general framework.
[Based on JHEP 01 (2021) 146 and Proc.Roy.Soc.Lond.A 476 (2020) 2237, 20200035]
The diphoton channel at lepton colliders, $e^+e^- (\mu^+\mu^-) \to \gamma \gamma$, has a remarkable feature that the leading new physics contribution comes only from dimension-eight operators. This contribution is subject to a set of positivity bounds, derived from fundamental principles of Quantum Field Theory, such as unitarity, locality, analyticity and Lorentz invariance. These positivity bounds are thus applicable to the most direct observable --- the diphoton cross sections. This unique feature provides a clear, robust, and unambiguous test of these principles. We estimate the capability of various future lepton colliders in probing the dimension-eight operators and testing the positivity bounds in this channel. We show that positivity bounds can lift certain flat directions among the effective operators and significantly change the perspectives of a global analysis. We also perform a combined analysis of the $\gamma\gamma/Z\gamma/ZZ$ processes in the high energy limit and point out the important interplay among them.
Based on 2011.03055
We consider the positivity bounds on dimension-8 four-electron operators and study two related phenomenological aspects at future lepton colliders. First, if positivity is violated, probing such violations will revolutionize our understanding of the fundamental pillars of quantum field theory and the S-matrix theory. Second, the positive nature of the dimension-8 parameter space allows us to either directly infer the existence of UV-scale particles together with their quantum numbers or exclude them in a model-independent way. We demonstrate with realistic examples how those possibilities can be achieved.
Many new physics models, e.g., compositeness, extra dimensions, extended Higgs sectors, supersymmetric theories, and dark sector extensions, are expected to manifest themselves in the final states with leptons and photons. This talk presents searches in CMS for new phenomena in the final states that include leptons and photons, focusing on the recent results obtained using the full Run-II data-set collected at the LHC.
Abstract
Recently, there has been great interest in beyond-the-Standard Model (BSM) physics involving new low-mass matter and mediator particles. One such model, U(1)T3R, proposes a new U(1) gauge symmetry under which only right-handed fermions of the standard model are charged, as well as the addition of new vector-like fermions (e.g., chi_t) and a new dark scalar particle (phi) whose vacuum expectation value breaks the U(1)T3R symmetry. For this work, we perform a feasibility study to
explore the mass ranges for which these new particles can be probed at the LHC. We consider the interaction pp -> chi_t + t + phi in which the top quark decays purely hadronically, the chi_t decays semileptonically (chi_t -> W + b -> I nu b), and the phi decays to two photons. The proposed search is expected to achieve a discovery reach with signal significance greater than 5sigma for chi_t masses up to 1.8 TeV and phi masses as low as 1 MeV, assuming an integrated luminosity of 3000 fb-1.
Vector like quarks appear in many theories beyond the Standard Model as a way to cancel the mass divergence for the Higgs boson. The talk will focus on the most recent results using 13 TeV pp collision data collected by the ATLAS detector. This presentation will address the analysis techniques, in particular the selection criteria, the background modelling and the related experimental uncertainties. The results and the complementarity of the various searches, along with the phenomenological implications, will be discussed.
Naturalness arguments for weak-scale supersymmetry favour supersymmetric partners of the third generation quarks with masses light enough to be produced at the LHC. The ATLAS experiment has a variety of analyses devoted to direct production of stops and sbottoms, exploiting novel reconstruction and analysis techniques. This talk presents recent results from these searches and their interpretation in both supersymmetric models and simplified associated-production dark matter models.
Results from the CMS experiment are presented for searches for supersymmetric stop and sbottom production. A variety of final state decays are considered with an emphasis on targeting difficult to reach kinematic regions. The searches use proton-proton collision data with luminosity up to 137 fb-1 recorded by the CMS detector at center of mass energy 13 TeV during the LHC Run 2
The direct pair-production of the tau-lepton super-partner, stau, is one of the most interesting channels to search for SUSY. First of all the stau is with high probability the lightest of the scalar leptons. Secondly the signature of stau pair production signal events is one of the most difficult ones, yielding to the 'worst' and so most global scenario for the searches. The current model-independent stau limits comes from analysis performed at LEP but they suffer from the low energy of this facility. The LHC exclusion reach extends to higher masses for large mass differences, but under strong model assumptions. The ILC, a future electron-positron collider with energy up to 1 TeV, is a promising scenario for SUSY searches. The capability of the ILC for determining exclusion/discovery limits for the stau in a model-independent way is shown in this contribution, together with an overview of the current state-of-the-art. A detailed study of the 'worst' scenario for stau exclusion/discovery taking into account the effect of the stau mixing on stau production cross-section and efficiency is presented. For selected benchmarks, the prospect for measuring masses and polarized cross-sections will be shown. The studies were done using the sgv fast simulation adapted to the ILD detector concept at the ILC.
In this talk, I will report the recent progresses on the foundation of unification theory and the projects on the space-based gravitation wave detections. I shall briefly outline that the foundation of the hyperunified field theory based on the maximum coherence motion principle and maximum entangled-qubits motion principle as well as gauge and scaling invariance principle enables us to make issues on the long-standing open questions, such as: what is made to be the fundamental building block of nature? What is acted as the fundamental interaction of nature? what brings about the fundamental symmetry of nature? what is the basic structure of spacetime? how many dimensions does spacetime have? what makes time difference from space? why is there only one temporal dimension? why do we live in a universe with only four dimensional spacetime? Why are there leptons and quarks more than one family? why are the existed leptons and quarks the chiral fermions with maximum parity violation? how does the fundamental symmetry govern basic forces? what is the nature of gravity? how does early universe get inflationary expansion? what is a dark matter candidate? what is the nature of dark energy? what is the nature of Higgs boson? how can we understand three families of chiral type leptons and quarks? It is expected that the gravitational wave detections with LISA and Taiji projects in space provide a new window for exploring the gravitational universe and possible new phenomena of unification theory.
We introduce WimPyDD, a modular, object–oriented and customizable Python code that calculates accurate predictions for the expected rates in WIMP direct–detection experiments within the framework of Galilean–invariant non–relativistic effective theory in virtually any scenario, including inelastic scattering, an arbitrary WIMP spin and a generic WIMP velocity distribution in the Galactic halo. WimPyDD exploits the factorization of the three main components that enter in the calculation of direct detection signals: i) the Wilson coefficients of the effective theory, that encode the dependence of the signals on the ultraviolet completion of the effective theory; ii) a response function that depends on the nuclear physics and on the features of the experimental detector (acceptance, energy resolution, response to nuclear recoils); iii) a halo function that depends on the WIMP velocity distribution and that encodes the astrophysical inputs. In WimPyDD these three components are calculated and stored separately for later interpolation and combined together only as the last step of the signal evaluation procedure. This makes the phenomenological study of the direct detection scattering rate with WimPyDD transparent and fast also when the parameter space of the WIMP model has a large dimensionality.
We briefly summarize some of several published results obtained with WimPyDD so far as illustrative examples of its power and flexibility.
The first results of the Fermilab Muon $g−2$ experiment are in full agreement with the previous BNL measurement and push the world average deviation in $\Delta a_\mu$ from the Standard Model to 4.2 $\sigma$. In this talk I will present an extensive survey of its impact on beyond the Standard Model physics, focusing on simple extensions of the standard model, based on arXiv:2104.03691. In this work we used state-of-the-art calculations and a sophisticated set of tools to make predictions for $a_\mu$, dark matter and LHC searches. We examined a wide range of simple models with up to three new fields which represent some of the few ways that large $\Delta a_\mu$ can be explained. The results show that the new measurement excludes a large number of models and provides crucial constraints on others. Generally, these models provide viable explanations of the $a_\mu$ result only by using rather small masses and/or large couplings with chirality flip enhancements, which can lead to conflicts with limits from LHC and dark matter experiments. I will present results for a range of models extending the standard model by one, two and three new fields including scalar leptoquarks and simple models constructed to explain dark matter and $g-2$ simultaneously.
A pseudo-Nambu-Goldstone boson (pNGB) is an attractive candidate for dark matter due to the simple evasion of the current severe limits of dark matter direct detection experiments. One of the pNGB dark matter models has been proposed based on a gauged U(1) B−L symmetry. The pNGB has long enough lifetime to be a dark matter and thermal relic abundance can be fit with the observed value against the constraints on the dark matter decays from the cosmic-ray observations. The pNGB dark matter model can be embedded into an SO(10) grand unified theory, whose SO(10) is broken to the Pati-Salam gauge group at the unified scale, and further to the Standard Model gauge group at the intermediate scale. Unlike the previous pNGB dark matter model, the parameters such as the gauge coupling constants and the gauge kinetic mixing are determined by solving the renormalization group equations for gauge coupling constants with appropriate matching conditions. From the constraints of the dark matter lifetime and gamma-ray observations, the pNGB dark matter mass must be less than O(100) GeV. We find that the thermal relic abundance can be consistent with all the constraints when the dark matter mass is close to half of the CP even Higg masses.
Different aspects of explicit dS proposals in string theory have recently come under intense scrutiny. One key ingredient is D7-brane gaugino condensation, which can be straightforwardly treated using effective 4d supergravity. However, it is also desirable to derive the relevant scalar potential directly from a 10d Lagrangian which captures the interactions among the various localized sources and the background fields. While progress in this endeavour has recently been made, issues related to divergences and non-localities related to the quartic gaugino coupling have remained problematic in the available proposals. I will discuss an explicitly local and finite D7-brane quartic gaugino term which reproduces the relevant part of the 4d supergravity action upon dimensional reduction. This is both a step towards a more complete understanding of 10d type-IIB supergravity as well as specifically towards better control of dS constructions in string theory involving gaugino condensation.
TBA
Reactor experiments provide an excellent platform to investigate the atomic ionization effects induced by the unexplored neutrino interaction channels. Including the atomic effects in our calculations, we study the neutrino-electron scattering by reactor anti-neutrinos in low-energy electron recoil detectors such as Si/Ge in light of neutrino non-standard interactions with leptons. We find that the atomic and crystal effects in Si/Ge yields a sizable suppression to the neutrino-electron scattering rate when compared to the free-electron approximation. We present our sensitivity results for the light vector and scalar mediator case. The explanation of the excess in the recent Xenon1T result can also be investigated at the reactor experiments since the reactors have a similar energy flux profile to solar neutrinos with characteristic neutrino energies <1 MeV.
Recent measurements of the germanium quenching factor deviate significantly from the predictions of the standard Lindhard model for nuclear recoil energies below a keV. This departure may be explained by the Migdal effect in neutron scattering on germanium. In this talk, we will discuss the Migdal effect on the quenching factor, We show it can mimic the signal of a light Z′ or light scalar mediator in coherent elastic neutrino-nucleus scattering experiments with reactor antineutrinos. It is imperative that the quenching factor of nuclei with low recoil energy thresholds be precisely measured close to threshold to avoid such confusion. This will also help in experimental searches of light dark matter.
The Forward Physics Facility (FPF) at LHC has the potential to explore the far-forward region at LHC. FASER$\nu$ is the dedicated program at FPF to study collider neutrinos. Charged current neutrino interactions have been extensively studied in the context of various experiments, including FASER$\nu$. The presence of a charged lepton in the final state allows for easy identification of candidate signal events and incoming beam energy reconstruction. Neutral current neutrino interaction on the other hand have a neutrino in the final state. This imposes two challenges: a) differentiating signal from background, which is primarily neutral hadron induced in FASER$\nu$ and b) reconstructing incoming beam energy when the final state has missing energy. In this work, we propose to use machine learning tools to identify and reconstruct signal events. We show how a suitable choice of event observables and proper training of the neural network can allow us to constrain NC neutrino cross-section in the 100GeV- a few TeV range. We convert this cross-section sensitivity to limits on neutrino NSI.
We introduce improved Leinartas algorithm, to simplify multivariate rational functions via partial fraction decomposition. We use this algorithm to simplify IBP reduction coefficients, dramatically shorten the size of the coefficients. This algorithm can also be used to simply rational functions in other fields of theoretical physics.
In this talk, we point out a novel signature of physics beyond the Standard Model which could potentially be observed both at the LHC and at future colliders. This signature, which emerges naturally within many proposed extensions of the Standard Model, results from the multiple displaced vertices associated with the successive decays of unstable, long-lived particles along the same decay chain. We call such a sequence of displaced vertices a "tumbler." We examine the prospects for observing tumblers at the LHC and assess the extent to which tumbler signatures can be distinguished from other signatures of new physics which involve multiple displaced vertices within the same collider event. As part of this analysis, we also develop a procedure for reconstructing the masses and lifetimes of the particles involved in the corresponding decay chains. We find that the prospects for discovering and distinguishing tumblers can be greatly enhanced by exploiting precision timing information — information such as would be provided by the CMS timing layer at the HL-LHC. Our analysis therefore provides strong motivation for continued efforts to improve the timing capabilities of collider detectors at the LHC and beyond.
Triggering long-lived particles (LLPs) at the first stage of the trigger system is very crucial in LLP searches to ensure that we do not miss them at the very beginning. The future High Luminosity runs of the Large Hadron Collider will have an increased number of pile-up events per bunch crossing. There will be major upgrades in hardware, firmware and software sides, like tracking at level-1 (L1). The L1 trigger menu will also be modified to cope with pile-up and maintain the sensitivity to physics processes. In our study we found that the usual level-1 triggers, mostly meant for triggering prompt particles, will not be very efficient for LLP searches in the 140 pile-up environment of HL-LHC, thus pointing to the need to include dedicated L1 triggers in the menu for LLPs. We consider the decay of the LLP into jets and develop dedicated jet triggers using the track information at L1 to select LLP events. We show in our work that these triggers give promising results in identifying LLP events with moderate trigger rates.
This talk discusses new techniques to detect signatures potentially originating from long-lived particles in the CMS detector, presents recent results from such searches in CMS using the full Run-II data-set of the LHC, and discusses prospects for Run-III.
In a fertile patch of the string landscape with the MSSM as the low energy EFT,
it is expected that soft terms scan as a power law thus favoring large soft terms.
This is to be balanced by the ABDS anthropic requirement that the pocket universe weak scale be not too far removed from our measured value. Under such conditions, the landscape predicts a Higgs mass of ~125 gev with sparticles beyond present LHC search limits and a higgsino as the LSP. Dark matter is expected to be mixed axion plus higgsino LSP.
Higgsinos are a particularly compelling form of dark matter, and are on the verge of detection by multiple current experimental avenues. They can arise in models with decoupled scalars that enjoy the benefits of depending on very few parameters while still explaining gauge coupling unification, dark matter, and most of the hierarchy between the Planck and electroweak scales, and they remain undetected to past experiments. My talk will cover the reach for current and upcoming electron electric dipole moment experiments as compared to direct and indirect detection as avenues to observe higgsino dark matter models.
I will show that color-breaking vacua may develop at high temperature in the Mini-Split SUSY scenario. This can lead to a nontrivial cosmological history of the universe, including strong first order phase transitions and domain wall production. Given the typical PeV energy scale associated with Mini-Split SUSY models, a stochastic gravitational wave background at frequencies around 100 Hz is expected. I will discuss the potential for detection of such a signal in future gravitational wave experiments.
In this talk, I discuss cosmological models that account for both inflation and the generation of net baryon asymmetry in the context of high-scale supersymmetry. Two different classes of inflationary models can be distinguished in which the gravitino mass is above or below the inflationary scale. When supersymmetry is broken at some high scale, the inflationary potential may be perturbed, which places restrictions on the model of inflation and supersymmetry breaking scale. Finally, I present the mass spectra of the inflationary sector and examine both thermal and non-thermal leptogenesis in high-scale supersymmetry.
We discuss a model with dark sector described by non-Abelian $SU(2)_D$ gauge symmetry where we introduce $SU(2)_L \times SU(2)_D$ bi-doublet vector-like leptons to generate active neutrino masses and kinetic mixing between $SU(2)_D$ and $U(1)_Y$ gauge fields at one-loop level. After spontaneous symmetry breaking of $SU(2)_D$, we have remnant $Z_4$ symmetry guaranteeing stability of dark matter candidates. We formulate neutrino mass matrix and related lepton flavor violating processes and discus dark matter physics estimating relic density. It is found that our model realize multicomponent dark matter scenario due to the $Z_4$ symmetry and relic density can be explained by gauge interactions with kinetic mixing effect.
Radiation produced by decaying/annihilating dark matter (DM) and evaporating primordial black holes (PBH) can ionize and heat up intergalactic medium (IGM) before reionization. Such effects can be efficiently probed using observations of cosmic microwave background (CMB) and 21cm signal of neutral hydrogen. In this talk I will show that CMB data from Planck and 21cm data from EDGES can set some of the most stringent and robust bounds on decay/annihilation rates of DM and abundance of PBH, future CMB missions can improve current Planck limits by up to two orders of magnitudes. This talk is partially based on our work in ArXiv 2002.03380 and 2011.12244.
We present a dark matter model to explain the excess events in the electron recoil data recently reported by the Xenon1T experiment. In our model, dark matter annihilates into a pair of on-shell particles , which subsequently decay into the final state; interacts with electrons to generate the observed excess events. Because of the mass hierarchy, the velocity of can be rather large and can have an extended distribution, providing a good fit to the electron recoil energy spectrum. We estimate the flux of from dark matter annihilations in the galaxy and further determine the interaction cross section, which is sizable but sufficiently small to allow to penetrate the rocks to reach the underground labs.
We study the prospects for indirect detection of dark matter (DM) in the Sun and in the Galactic halo using the Hyper-Kamiokande (HyperK) neutrino experiment, currently under construction. We undertook a dedicated simulation of the HyperK detector, which we benchmarked against results from the Super-Kamiokande (SuperK) experiment and HyperK physics projections. For DM annihilation to neutrino final states in the Galactic halo, we find that HyperK will be sensitive to thermal annihilation cross-sections for DM with mass around 20-40 MeV, assuming an NFW halo profile. For neutrino signals produced via the annihilation of DM captured in the Sun, we determined the HyperK sensitivity to the DM spin-dependent scattering cross-section for various standard model final states. We find that HyperK will improve upon current SuperK limits by a factor of 2-3, with a further improvement in sensitivity possible if systematic errors can be decreased relative to SuperK.
White dwarfs are the most abundant stellar remnants. They provide a promising means of probing dark matter (DM) interactions complimentary to direct searches. The scattering of DM off stellar constituents, ions or degenerate electrons, leads to gravitational capture, with important observational consequences. In particular, white dwarf heating due to the energy transfer in the DM capture and subsequent annihilation can occur in white dwarfs located in DM-rich environments. In this case, the DM-nucleon/electron scattering cross sections can be constrained by comparing the heating rate due to captured DM with observations of cold white dwarfs. We apply this technique to observations of old white dwarfs in the globular cluster Messier 4, which we assume to be formed in a DM subhalo. We consider the capture of DM by scattering off either ions or degenerate electrons. For ions, we account for the stellar structure, the star opacity, realistic nuclear form factors and finite temperature effects relevant to sub-GeV DM. Electrons are treated as relativistic, degenerate targets, with Pauli blocking, finite temperature and multiple scattering effects all taken into account. We also estimate the DM evaporation rate for both targets. For DM-nucleon scattering, we find that white dwarfs can probe the sub-GeV mass range inaccessible to direct detection experiments, with the low mass reach limited only by evaporation, and can be competitive with direct detection in the 1GeV−10TeV range. White dwarf limits on DM-electron scattering are found to outperform current electron recoil experiments over the full mass range considered, and extend well beyond the ~10 GeV mass regime where the sensitivity of electron recoil experiments is reduced.
Cosmic photons from astrophysical sources are ideal for investigating the Lorentz symmetry violation (LV). A series of studies on high energy gamma-ray burst (GRB) photons suggest a light speed variation with linear energy dependence at the Lorentz violation scale of $3.6*10^{17}$ GeV, with subluminal propagation of high energy photons in cosmological space. Constraints on Lorentz violation from recent observation of PeV scale photons from LHAASO collaboration are also discussed.
The talk will address the potential of the muon collider to probe Supersymmetry and related ideas for physics Beyond the Standard Model.
The proposed Circular Electron Positron Collider (CEPC) with a center-of-mass energy √ s = 240 GeV will serve as a Higgs factory, while it can offer good opportunity for new physics search at low energy, which is challenging in hadron colliders but motivated by some theory models such as dark matter. This talk will cover electroweak SUSY and slepton search prospects at CEPC.
We study the impact of future electron-positron colliders, such as CEPC, ILC and FCC-$ee$, on global fits of the simplest supersymmetric models, such as the CMSSM and pMSSM-7, using GAMBIT and publicly available data published by the GAMBIT Community. From the impact of the additional likelihoods, we discuss the discovery prospects and reaches of future colliders.
Future lepton colliders such as the Circular Electron Positron Collider (CEPC) and FCC (Future Circular Collider)-ee would run as high-luminosity $Z$-boson factories, which offer a unique opportunity to study long-lived particles which couple to $Z$-bosons. We consider the long-lived lightest neutralinos in the R-parity-violating supersymmetry, produced from $Z$-boson decays, and show the sensitivity limits of not only the near detectors at the CEPC and FCC-ee but also proposed far-detector experiments at these colliders. We find the near detectors at the future $Z$-factories can outperform the ATLAS experiment at the high-luminosity Large Hadron Collider (LHC) and the proposed LHC experiments with far detectors (AL3X, CODEX-b, FASER, and MATHUSLA), and that new experiments with far detectors at future lepton colliders may extend and complement the sensitivity reaches of the default near detectors.
We initiate the study of a three dimensional disordered supersymmetric field theory. Specifically, we consider a N = 2 large N Wess-Zumino like model with cubic superpotential involving couplings drawn from a Gaussian random ensemble. Taking inspiration from analyses of lower dimensional SYK like models we demonstrate that the theory flows to a strongly coupled superconformal fixed point in the infra-red. In particular, we obtain leading large N spectral data and operator product coefficients at the critical point. Moreover, the analytic control accorded by the model allows us to compare our results against those derived in the conformal bootstrap program and demonstrate consistency with general expectations.
A wealth of physical information may be inferred from the singularities of scattering amplitudes. For the simplest interacting gauge theory, these singularities have been found to be encoded in beautiful mathematical objects known as cluster algebras. In this talk, I present evidence that cluster algebras may underlie the analytic structure of general quantum field theories. In particular, I show that they describe the singularities of a considerable number of Feynman integrals in dimensional regularization, most notably those governing Higgs plus jet amplitudes in QCD. This opens for the first time the exciting prospect of applications of cluster algebras to future collider physics calculations, for example via novel bootstrap methods that evade the formidable task of direct integration.
We show that using the full tower information in the form of an image,
a Convolutional Neural Network(CNN) can efficiently recognise Vector boson fusion(VBF)
signal from non VBF backgrounds at the Large Hadron Collider(LHC). As a concrete example, we compare with existing state-of-the-art techniques currently in use, we show that deep-learning algorithms like a CNN can significantly improve the bounds on the invisible branching ratio of the recently discovered Higgs boson. This can help constrain many beyond the Standard Model(BSM) theories, which relies on the Higgs decaying to any new stable (or semi stable) particles which do not interact with the known Standard Model particles.
Based on the jet image approach, which treats the energy deposition in each calorimeter cell as the pixel intensity, the Convolutional neural network (CNN) method has been found to achieve a sizable improvement in jet tagging compared to the traditional jet substructure analysis.
In this work, the Mask R-CNN framework is adopted to reconstruct Higgs jets in collider-like events, with the effects of pileup contamination taken into account. This automatic jet reconstruction method achieves higher efficiency of Higgs jet detection and higher accuracy of Higgs boson four-momentum reconstruction than traditional jet clustering and jet substructure tagging methods.
Moreover, the Mask R-CNN trained on events containing a single Higgs jet is capable of detecting one or more Higgs jets in events of several different processes, without apparent degradation in reconstruction efficiency and accuracy.
The outputs of the network also serve as new handles for the $t\bar{t}$ background suppression, complementing to traditional jet substructure variables.
During the upcoming Run 3, a new experimental program will be initiated at the LHC in its far-forward region that will focus on the search for highly-displaced decays of light unstable BSM particles in the FASER detector and on studying interactions of high-energy neutrinos in the FASERnu and SND@LHC experiments. To fully exploit the relevant physics potential, the experimental efforts should be supplemented with a comprehensive program of theoretical and phenomenological studies. To facilitate this, in the talk, we will introduce a numerical package, namely the FORward Experiment SEnsitivity Estimator, or FORESEE, which could be used to obtain the expected sensitivity reach for BSM models in various far-forward experiments. We will also comment on the similar prospects for the far-forward BSM searches in the future HE-LHC, SppC, and FCC-hh hadron colliders.
We investigate simplified models involving an inert scalar triplet and vector-like leptons that can account for the muon g−2 anomaly. These simplified scenarios are embedded in a model that features W' and Z' bosons, which are subject to stringent collider bounds. The constraints coming from the muon g−2 anomaly are put into perspective with collider bounds, as well as bounds coming from lepton flavor violation searches. The region of parameter space that explains the g−2 anomaly is shown to be within reach of lepton flavor violation probes and future colliders such as HL-LHC and HE-LHC.
The semileptonic B-decay anomalies could be a gateway to new physics. Of the theories and BSM models put forward, the vector charge-2/3 $U_1$ leptoquark (LQ) seems to be the best candidate to explain the anomalies seen in the $R_{D^{(*)}}$ and $R_{K^{(*)}}$ observables. In this talk, I will explore the LHC bounds on the $U_1$ leptoquark model. I will present a list of possible scenarios with different coupling combinations that can contribute to the relevant operators. I will then discuss how the latest dilepton data and the direct search data can either limit or exclude these scenarios. Finally, I would show how an LQ of mass of about 1.5 TeV survives the LHC and other flavour bounds and explain the anomalies simultaneously.
In this talk, we present an extension of the SM featuring vector-like leptons and uncharged scalars in the BSM sector. We show that this theory allows to accommodate for the discrepancies in both the muon and electron anomalous magnetic moments simultaneously, without explicit violation of lepton flavor universality. Moreover, the theory remains physical and predictive until the Planck scale and stabilizes the Higgs potential. We also highlight the most prominent phenomenological implications.
While the hunt for new states beyond the standard model (SM) goes on for various well motivated theories, the leptoquarks are among the most appealing scenarios at recent times due to a series of tensions observed in B−decays. We consider two scalar leptoquarks, one being a singlet and the other a triplet under the electroweak gauge group, and respectively contributes to charged and neutral current B-decays. The final state consisting of a b and τ jets provides highest reach for the singlet leptoquark whereas for the triplet leptoquark 1 − jet + 2μ+ ̸pT topology is the most optimistic signature at the hadron colliders. Various distinguishing signatures are studied which can easily discriminate different components of the triplet leptoquark. Establishing a direct connection with the neutral current B-anomalies, we perform simulations for these leptoquarks at the proposed multi-TeV muon collider where the background free environment can probe O(10−2) value of the leptoquark couplings to fermions up to the 10 TeV leptoquark mass range
The recent experimental result on the muon g-2 from Fermilab has confirmed the old Brookhaven result and increased the tension with the Standard Model. We investigate the electroweak sector of supersymmetry to explain the muon g-2 anomaly. We perform a scan of the SUGRA parameter space with the help of a neural network to identify the regions consistent with the g-2 anomaly. It is shown that a gluino-driven radiative breaking of the electroweak symmetry is a natural outcome with the sleptons and weakinos being low-lying while the colored sector is heavy. To perform a SUSY search at the LHC using a set of benchmarks, we employ a deep neural network to train the signal and background. We show that benchmarks corresponding to slepton and sneutrino production can be discovered at HL-LHC and HE-LHC.
The talk is based on arXiv:2104.03839 [hep-ph].
We demonstrate the impact of non-perturbative effects on the annihilation cross section of DM in a model of simplified t-channel DM. Specifically, we study the case of Majorana fermion DM coupling to the standard model (SM) quarks via a colored scalar.
For DM masses in the GeV-TeV range, direct detection experiments strongly constrain the DM coupling to the SM quarks. From a cosmological point of view however, a large coupling to the SM is not mandatory if the mass splitting between the colored scalar and the DM candidate is sufficiently small. This region of the parameter space is subject to non-perturbative effects, namely the Sommerfeld effect and bound state formation, which can significantly enhance the effective DM annihilation cross section.
We present the impact of this effect on current and upcoming collider searches as well as direct detection experiments.
We examine the implications of non-standard cosmologies (NSCs) on Dark Matter. We present a detailed analysis of the impact of NSCs on frozen-in relics and examine their lower allowed mass limit. Moreover, we discuss how the ``natural" axion window can be extended, which can potentially help us to exclude NSCs once the axion is discovered.
High energy $e^+e^-$ colliders offer unique possibility for the most general search for dark matter (DM) based on the mono-photon signature. As any $e^+e^-$ collision processmay include hard initial-state photon radiation, analysis of the energy spectrum and angular distributions of observed photons can be used to search for hard processes with an invisible final state.
We consider production of DM particles at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments via a mediator exchange. Dedicated procedure of merging the matrix element calculations with the lepton ISR structure function was developed to model the Standard Model background processes contributing to mono-photon signature with WHIZARD.
Detector effects are taken into account within the DELPHES fast simulation framework. Limits on the light DM production cross section in a simplified model are set as a function of the mediator mass and width based on the expected two-dimensional distributions of the reconstructed mono-photon events.
Limits on the mediator couplings are then presented for a wide range of mediator masses and widths. For light mediators, for masses up to the centre-of-mass energy of the collider, coupling limits derived from the mono-photon analysis are more stringent than those expected from direct resonance searches in decay channels to SM particles.
We study the connection between neutrino mass and two unsolved cosmological problems: the existence of dark matter (DM) and matter-antimatter asymmetry. To have a testable connection, we consider the low energy type Ib seesaw mechanism instead of the traditional type I seesaw mechanism. In the minimal type Ib seesaw mechanism, the effective neutrino mass operator involves two different Higgs doublets, and two right-handed neutrinos form a (pseudo-) Dirac pair. The DM candidate can be included by adding a neutrino portal with a dark fermion and a dark scalar, while the baryon asymmetry can be approached through resonant leptogenesis in an extended model where the type Ib seesaw mechanism is realised effectively. We explore the parameter space of the models consistent with both oscillation data and observations. Within this framework, we show how DM and leptogenesis can be directly related to laboratory experiments for a heavy Dirac neutrino mass around 1~100 GeV.
Innovative experimental techniques are needed to further search for dark matter weakly interacting massive particles. The ultimate limit is represented by the ability to efficiently reconstruct and identify nuclear and electron recoil events at the experimental energy threshold. Gaseous Time Projection Chambers (TPC) with optical readout are very promising candidates thanks to the 3D event reconstruction capability of the TPC technique and the high sensitivity and granularity of last generation scientific light sensors. The Cygno experiment is pursuing this technique by developing a TPC operated with He(Ar)-CF4 gas mixture at atmospheric pressure equipped with a Gas Electron Multipliers (GEM) amplification stage that produces visible light collected by scientific CMOS camera. A fast photodetector is used to measure the drift time of the primary ionisation electrons and thus reconstruct the third coordinate of the ionisation track. Events are then reconstructed with an innovative multi-stage pattern recognition algorithm based on advanced clustering techniques. In this contribution, we present the performances of prototype detectors assessed by exposing them to radioactive sources. We show that good energy and spatial resolution as well as discriminating power between nuclear and electron recoils is achieved in the KeV energy range. Finally, we discuss the plan to build a 1m3 demonstrator expected to be installed and operated at LNGS in 2021/22. This experimental campaign aims at proving the scalability of such a detector concept to a bigger apparatus able to significantly extend our knowledge about DM and neutrinos.
Searches in CMS for dark matter particles, mediators, and dark sector extensions will be presented. Various final states, topologies, and kinematic variables are explored utilizing the full Run-II data-set collected at the LHC.
The formation of primordial black hole (PBH) dark matter and the generation of scalar induced secondary gravitational waves (SIGWs) have been studied in the generic no-scale supergravity inflationary models. By adding an exponential term to the K\"ahler potential, the inflaton experiences a period of ultra-slow-roll and the amplitude of primordial power spectrum is enhanced to $\mathcal{O}(10^{-2})$. The enhanced power spectra of primordial curvature perturbations can have both sharp and broad peaks. A wide mass range of PBH is realized in our model, and the frequencies of the scalar induced gravitational waves are ranged form nHz to Hz. We show three benchmark points where the PBH mass generated during inflation is around $\mathcal{O}(10^{-16}M_{\odot})$, $\mathcal{O}(10^{-12}M_{\odot})$ and $\mathcal{O}(M_{\odot})$. The PBHs with masses around $\mathcal{O}(10^{-16}M_{\odot})$ and $ \mathcal{O}(10^{-12}M_{\odot})$ can make up almost all the dark matter, and the associated SIGWs can be probed by the upcoming space-based gravitational wave (GW) observatory. Also, the wide SIGWs associated with the formation of solar mass PBH can be used to interpret the stochastic GW background in the nHz band, detected by the North American Nanohertz Observatory for Gravitational Waves, and can be tested by future interferometer-type GW observations.
In this talk I will discuss about Higgs inflation in the framework of a minimal extension of the Standard Model gauge symmetry by a U(1)_B−L factor. Furthermore I will talked about physics related to the nature of gravitino, considering possible scenarios, including that it is the lightest supersymmetric particle (LSP) where it can be considered as a DM candidate. The other possibility including the gravitino is not the LSP, then we have a short lived gravitino and a long-lived depending upon the mass range of gravitino.
We discuss supergravity inflation in braneworld cosmology for the class of potentials $V(\phi)=\alpha \phi^n\rm{exp}(-\beta^m \phi^m)$ with $m=1,~2$. These minimal SUGRA models evade the $\eta$ problem due to a broken shift symmetry and can easily accommodate the observational constraints. In the high energy regime $V/\lambda\gg 1$, the numerical predictions and approximate analytic formulas are given for the scalar spectral index $n_s$ and tensor-to-scalar ratio $r$. The models with smaller $n$ are preferred while the models with larger $n$ are out of the $2\sigma$ region. Remarkably, the $\rho^2/\lambda$ correction to the energy density in Friedmann equation results in sub-Planckian inflaton excursions $\Delta\phi <1$.
We consider Hybrid inflation and Tribrid Inflation models in no-scale supergravity framework. We show that a Starobinsky like inflation can be realized with asymptotically flat potentials. U(1)_R symmetry can be broken on the renormalizable level or by Planck suppressed non-renormalizable operators. A connection to the low energy physics as well as the neutrino masses is addressed.
Extensions of the Standard Model (SM) Higgs sector allow for a rich cosmological history around the electroweak (EW) scale. In the context of the next-to 2HDM (N2HDM) we analyse the phenomena of EW symmetry non-restoration as well as vacuum trapping. We show that these phenomena can occur in relevant parts of the parameter space. Focusing on the type II N2HDM and taking into account various theoretical and experimental constraints, we demonstrate how these novel finite-temperature effects are related and how they can be used to further constrain the parameter space of the model. In particular, we show that the presence of a global EW minimum at zero temperature might not be a sufficient requirement for the validity of the vacuum configuration.
In the ''Minimal Supergravity Inflation'', whose only degrees of freedom are the (real) inflaton, gravitino, and graviton, an issue of the catastrophic production of slow gravitinos after inflation has been reported. We will briefly comment on the origin of such catastrophic production and propose an alternative model with the same physical degrees of freedom that is free from the issue. We utilize a cubic nilpotent superfield to realize it and demonstrate that inflation is possible in this framework. However, even though there is no issue of gravitino production related to the sound-speed change, the standard gravitino problem turns out to be severe.
The Nelson-Seiberg theorem and its extension relate supersymmetry breaking and R-symmetries in Wess-Zumino models, and found applications in phenomenology model building. We show that there are counterexample models with generic superpotential coefficients and non-generic R-charge assignment for fields. These models have more R-charge 2 fields than R-charge 0 fields, but give SUSY vacua with spontaneous R-symmetry breaking. So they are counterexamples to both the Nelson-Seiberg theorem and its extensions. The pattern of R-charge assignment is discussed, and we provide a sufficient condition for counterexamples.
We study real higher-order constraints for ${\cal N}=1$ and ${\cal N}=2$ chiral superfields, which describe spontaneously broken (to ${\cal N}=0$) and non-linearly realized supersymmetry in the presence of a light axion of a spontaneously broken global $U(1)$. For ${\cal N}=1$ the constraint is of third order, while for ${\cal N}=2$ it is of fifth order and can be imposed on abelian vector or tensor (linear) multiplet. In both cases the constraint eliminates a single real scalar (saxion) in terms of goldstino field(s).
I will discuss various aspects of supersymmetric systems from the point of view of the theory of computational complexity. These include the claim that computing the Witten index of N=2 quantum mechanics is #P-complete and thus intractable. I will also discuss the complexity of finding supersymmetric ground states of local SUSY Hamiltonians and its implications for the problem of computing certain cohomology groups.
We show that the four-dimensional Chern-Simons theory studied by Costello, Witten and Yamazaki, is, with Nahm pole-type boundary conditions, dual to a boundary theory that is a three-dimensional analogue of Toda theory with a novel 3d W-algebra symmetry. By embedding four-dimensional Chern-Simons theory in a partial twist of the five-dimensional maximally supersymmetric Yang-Mills theory on a manifold with corners, we argue that this three-dimensional Toda theory is dual to a two-dimensional topological sigma model with A-branes on the moduli space of solutions to the Bogomolny equations. This furnishes a novel 3d-2d correspondence, which, among other mathematical implications, also reveals that modules of the 3d W-algebra are modules for the quantized algebra of certain holomorphic functions on the Bogomolny moduli space.
I will discuss the current status of the production of stochastic GW backgrounds by cosmological phase transitions. Main focus will be the differences between fully hydrodynamic simulations and the recently presented hybrid approach. I will also touch on recent results on the energy budget of the phase transition and the LISA sensitivity forecasts using likelihood sampling.
Based on arXiv: 2004.06995, 2010.00971, 2107.06275.
We will discuss energy budget of first order phase transitions and identify models capable of supporting extreme supercooling necessary to feature bubble collisions as the main source of gravitational waves. We will also review the new semi-analytical calculation of the spectrum appropriate in such strong transitions.
Over the next few decades, we will have an exciting opportunity to detect GWs from the early Universe with space interferometers. In this talk, we first propose an efficient numerical scheme to calculate GWs from sound waves in first-order phase transitions, which reveals more detailed structure of the spectrum. Based on this simulation, we next discuss the possibility of the enhancement of the GW signal in the presence of density perturbations. The first part is based on 2010.00971 with T. Konstandin and H.Rubira (DESY), while the second part is based on an ongoing work with T. Konstandin, H. Rubira, and J. van de Vis (DESY).
I discuss to what extend LISA can observe features of gravitational wave spectra originating from cosmological first-order phase transitions. I focus on spectra which are of the form of double-broken power laws. These spectra are predicted by hydrodynamic simulations and also analytical models such as the sound shell model. I argue that the ratio of the two break frequencies is an interesting observable since it can be related to the wall velocity while overall amplitude and frequency range are often degenerate for the numerous characteristics of the phase transition. The analysis uses mock data obtained from the power spectra predicted by the simplified simulations and the sound shell model and analyzes the detection prospects using chi^2 -minimization and likelihood sampling. I point out that the prospects of observing two break frequencies from the electroweak phase transition is hindered by a shift of the spectrum to smaller frequencies for strong phase transitions. Finally, I also highlight some differences between signals from the sound shell model compared to simulations.
We study gravity wave production and baryogenesis at the electroweak phase transition in a real singlet scalar extension of the Standard Model, including vectorlike top partners, to generate the CP violation needed for electroweak baryogenesis (EWBG). The singlet makes the phase transition strongly first order through its coupling to the Higgs boson, and it spontaneously breaks CP invariance through a dimension-five contribution to the top quark mass term, generated by integrating out the heavy top quark partners. We improve on previous studies by incorporating updated transport equations, compatible with large bubble wall velocities. The wall speed and thickness are computed directly from the microphysical parameters rather than treating them as free parameters, allowing for a first-principles computation of the baryon asymmetry. The size of the CP-violating dimension-five operator needed for EWBG is constrained by collider, electroweak precision, and renormalization group running constraints. We identify regions of parameter space that can produce the observed baryon asymmetry or observable gravitational wave (GW) signals. Contrary to standard lore, we find that for strong deflagrations, the efficiencies of large baryon asymmetry production and strong GW signals can be positively correlated. However, we find the overall likelihood of observably large GW signals to be smaller than estimated in previous studies. In particular, only detonation-type transitions are predicted to produce observably large gravitational waves.
In order to solve the hierarchy problem, the relaxion must remain trapped in the correct minimum, even if the electroweak symmetry is restored after reheating. In this scenario, the relaxion starts rolling again until the back-reaction potential, with its set of local minima, reappears. Depending on the time of barrier-reappearance, Hubble friction alone may be insufficient to re-trap the relaxion in a large portion of the parameter space. Thus, an additional source of friction is required, which might be provided by coupling to a dark photon. The dark photon experiences a tachyonic instability as the relaxion rolls, which slows down the relaxion by backreacting to its motion, and efficiently creates anisotropies in the dark photon energy-momentum tensor, sourcing gravitational waves. We calculate the spectrum of the resulting gravitational wave background from this new mechanism, and evaluate its observability by current and future experiments. We further investigate the possibility that the coherently oscillating relaxion constitutes dark matter and present the corresponding constraints from gravitational waves.
I review new tools for the computation of Kaluza-Klein mass spectra associated with compactifications around various background geometries relevant for string theory. This includes geometries with little to no remaining symmetries, hardly accessible to standard methods. The new tools build on exceptional field theory, the duality covariant formulation of supergravity. Applications include the identification of non-supersymmetric AdS4 vacua which are perturbatively stable at all Kaluza-Klein levels.
I will describe the four-derivative corrections to four-dimensional N=2 minimal gauged supergravity and show that they are controlled by two constants. Interestingly, the solutions of the equations of motion in the two-derivative theory are not modified by the higher-derivative corrections. I will use this to arrive at a general formula for the regularized on-shell action for any asymptotically locally AdS_4 solution of the theory and show how the higher-derivative corrections affect black hole thermodynamic quantities in a universal way. I will employ these results in the context of holography to derive new explicit results for the subleading corrections in the large N expansion of supersymmetric partition functions on various compact manifolds for a large class of three-dimensional SCFTs arising from M2-branes. I will also briefly discuss possible extensions and generalizations of these results.
We discuss supergravity solutions that are holographically dual to supersymmetric CFTs that arise when various branes wrap a spindle. A spindle is a specific two dimensional orbifold: a two sphere with quantised conical deficits at each of the poles. We construct solutions describing the wrapped branes in gauged supergravity and then uplift them to D=10 and D=11 supergravity. Remarkably, in some cases the higher dimensional solutions are free from all orbifold singularities. For the case of D3 and M5 branes wrapping spindles we can calculate the central charge of the CFT that arises both from the gravity solution and from a field theory computation and find exact agreement. For the case of M2 branes there is an interesting connection with D=4 accelerating black holes.
We propose a model-independent framework to classify and study neutrino mass models and their phenomenology. The idea is to introduce one particle beyond the Standard Model which couples to leptons and carries lepton number together with an operator which violates lepton number by two units and contains this particle. This allows to study processes which do not violate lepton number, while still working with an effective field theory. The contribution to neutrino masses translates to a robust upper bound on the mass of the new particle. We compare it to the stronger but less robust upper bound from Higgs naturalness and discuss several lower bounds.
We propose a leptoquark model with two scalar leptoquarks $S^{}_1 \left( \bar{3},1,\frac{1}{3} \right)$ and $\widetilde{R}^{}_2 \left(3,2,\frac{1}{6} \right)$ to give a combined explanation of neutrino masses, lepton flavor mixing and the anomaly of muon $g-2$, satisfying the constraints from the radiative decays of charged leptons. The neutrino masses are generated via one-loop corrections resulting from a mixing between $S^{}_1$ and $\widetilde{R}^{}_2$. With a set of specific textures for the leptoquark Yukawa coupling matrices, the neutrino mass matrix possesses an approximate $\mu$-$\tau$ reflection symmetry with $\left( M^{}_\nu \right)^{}_{ee} = 0$ only in favor of the normal neutrino mass ordering. We show that this model can successfully explain the anomaly of muon $g-2$ and current experimental neutrino oscillation data under the constraints from the radiative decays of charged leptons.
In this seminar, we consider a set of new symmetries in the SM: {\it diagonal reflection} symmetries $R \, m_{u,\nu}^{*} \, R = m_{u,\nu}, ~ m_{d,e}^{*} = m_{d,e}$ with $R =$ diag $(-1,1,1)$. These generalized $CP$ symmetries predict the Majorana phases to be $\alpha_{2,3} /2 \sim 0$ or $\pi /2$.
By combining the symmetries with the four-zero texture, the mass eigenvalues and mixing matrices of quarks and leptons are reproduced well.
This scheme predicts the normal hierarchy, the Dirac phase $\delta_{CP} \simeq 203^{\circ},$ and $|m_{1}| \simeq 2.5$ or $6.2 \, $[meV].
In this scheme, the type-I seesaw mechanism and a given neutrino Yukawa matrix $Y_{\nu}$ completely determine the structure of the right-handed neutrino mass $M_{R}$. A $u-\nu$ unification predicts the mass eigenvalues to be $ (M_{R1} \, , M_{R2} \, , M_{R3}) = (O (10^{5}) \, , O (10^{9}) \, , O (10^{14})) \, $[GeV].
[This is talk will be on Phys.Rev. D100 (2019) no.3, 035009 by Soumita Pramanick]
Using $S3\times Z_2$ symmetry a scotogenic model for realistic neutrino mixing
at one-loop level will be discussed. In this model, there are two right-handed neutrinos.
It was found when these two right-handed neutrinos are mixed maximally one can obtain the
form of the left-handed Majorana neutrino mass matrix with $\theta_{13}=0$, $\theta_{23}=\pi/4$
and the solar mixing $\theta_{12}$ can have any value like that of Tribimaximal (TBM), Bimaximal (BM) and Golden Ratio (GR) or any other mixing scenario.
A little shift from the maximal mixing between the two right-handed neutrino states can yield the
realistic neutrino mixing angles i.e., non-zero $\theta_{13}$, deviation of $\theta_{23}$ from $\pi/4$
and small corrections to $\theta_{12}$.
Thus this scotogenic mechanism at one-loop level produces non-zero $\theta_{13}$ by shifting from maximal
mixing between the two-right handed neutrinos. The model also has two inert $SU(2)_L$ doublet scalars odd under $Z_2$, the lightest among which can become a dark matter.
The finite modular symmetry provides us with an attractive and novel way to understand lepton flavor mixing, and has recently attracted a lot of attention. In a class of neutrino mass models with modular flavor symmetries, it has been observed that CP symmetry is preserved at the stabilizer of the modulus parameter $\tau = {\rm i}$, whereas significant CP violation emerges within the neighbourhood of this stabilizer. In this work, we first construct a viable model with the modular $A^\prime_5$ symmetry, and explore the phenomenological implications for lepton masses and flavor mixing. Then, we introduce explicit perturbations to the stabilizer at $\tau = {\rm i}$, and present both numerical and analytical results to understand why a small deviation from the stabilizer leads to large CP violation. As low-energy observables are very sensitive to the perturbations to model parameters, we further demonstrate that the renormalization-group running effects play an important role in confronting theoretical predictions at the high-energy scale with experimental measurements at the low-energy scale.
We present a systematic investigation on simple inverse seesaw models for neutrino masses and flavor mixing based on the modular $S^{}_4$ symmetry. Two right-handed neutrinos and three extra fermion singlets are introduced to account for light neutrino masses through the inverse seesaw mechanism and to provide a keV-mass sterile neutrino as the candidate for warm dark matter in our Universe. Considering all possible modular forms with weights no larger than four, we obtain twelve models, among which we find one is in excellent agreement with the observed lepton mass spectra and flavor mixing. Moreover, we explore the allowed range of the sterile neutrino mass and mixing angles, by taking into account the direct search of $X$-ray line and the Lyman-$\alpha$ observations. The model predictions for neutrino mixing parameters and the dark matter abundance will be readily testable in future neutrino oscillation experiments and cosmological observations.
The Higgs boson mass has turned into a precision observable with an uncertainty of a few hundred MeV at the LHC and provides an important constraint on the parameter space of supersymmetric models. To have sensible limits, the experimental accuracy has to be matched by the precision of the theory predictions. Consequently, a tremendous effort has been put in the computation of the higher-order corrections to supersymmetric Higgs boson masses.
In this talk, we report about our computation of the ${\cal O\left(\alpha_t+\alpha_\lambda+\alpha_\kappa\right)^2}$ two-loop corrections to the Higgs boson masses of the CP-violating Next-to-Minimal Supersymmetric Standard Model (NMSSM) using the Feynman-diagrammatic approach. We discuss the renormalization schemes used for the Higgs sector and the top/stop sector, together with the treatment of the infrared divergences which appear in the gaugeless and zero momentum approximation. We present the numerical impact of the new corrections and their dependence on the renormalization scheme and the renormalization scale. Our new corrections have been implemented in the Fortran code ${\bf NMSSMCALC}$ that computes the Higgs mass spectrum of the CP-conserving and CP-violating NMSSM as well as the partial decay widths of the Higgs bosons including the state-of-the-art higher-order corrections. Our results mark another step forward in the program of increasing the precision in the NMSSM Higgs boson observables.
The Next-to-Minimal Supersymmetric extension of the Standard Model (NMSSM) including additionally six leptonic singlet superfields can explain the small active neutrinos masses via the inverse seesaw mechanism (ISS), while it still allows for large values of the neutrino Yukawa couplings with a mass scale of sterile neutrinos of order TeV. While $R$-parity is conserved in this model, lepton number is explicitly violated. The extended (s)neutrino sector therefore can affect the Higgs sector and the lepton flavor-violating observables through radiative corrections. We investigated these impacts by computing the complete one-loop corrections with full momentum dependence and consistently combined them with the dominant two-loop corrections at $ \mathcal{O}(\alpha_s\alpha_t + \alpha_t^2) $ to the Higgs boson masses and their mixings. We further computed the radiative decays $ l_i \to l_j + \gamma $, and the oblique parameters $ S,T,U$ at one-loop level. In our numerical study, we showed that these impacts can be significant depending on the parameter space. We take into account the constraints from the Higgs data, the neutrino oscillation data, the lepton flavor-violating decays, and the oblique parameters to have a realizable analysis. Our computations have been implemented in the public Fortran code $ \mathtt{NMSSMCALC}$-$\mathtt{nuSS} $ that computes the Higgs mass spectrum as well as the Higgs boson decay widths including the state-of-the-art higher-order corrections.
In light of the current situation that no direct sign of new particles has been observed so far,indirect searches of new particles become increasingly important.
Accurate theoretical predictions are inevitable in order to be able to indirectly find new physics and - in case of discovery - to identify the underlying model.
In this study, we calculated the full one-loop corrections to the decay widths of charged Higgs boson decays in the framework of the Next-to-Minimal Supersymmetric Model (NMSSM) with CP violation.
In this talk, we discuss the impact of the NLO corrections on the charged Higgs branching ratios in a wide range of parameter space that is compatible with the experimental constraints.
I discuss the general Three-Higgs Doublet Model (3HDM) and identify all limits that lead to exact SM alignment. I focus on the most economic setting, called here the Maximally Symmetric Three-Higgs Doublet Model (MS-3HDM). The potential of the MS-3HDM obeys an Sp(6) symmetry, softly broken by bilinear masses and explicitly by hypercharge and Yukawa couplings through renormalisation-group effects, whilst the theory allows for quartic coupling unification up to the Planck scale. Besides the two ratios of vacuum expectation values, $\tan\beta_{1,2}$, the MS-3HDM is predominantly governed by only three input parameters: the masses of the two charged Higgs bosons and their mixing angle σ. Most remarkably, with these input parameters, we obtain definite predictions for the entire scalar mass spectrum of the theory, as well as for the SM-like Higgs-boson couplings to the gauge bosons and fermions. The predicted deviations of these couplings from their SM values might be probed at future precision high-energy colliders.
Charginos and neutralinos are often the lightest new particles predicted by a wide range of supersymmetry models, and the lightest neutralino is a well motivated and studied candidate for dark matter in models with R-parity conservation. The small direct production cross sections of electroweakinos leads to difficult searches, despite relatively clean final states. This talk will highlight the most recent results of searches performed by the ATLAS experiment for charginos and neutralinos, covering a variety of model parameters and final states.
In this talk, I will give an overview of the status and recent developments of FeynHiggs. Focusing on the calculation of the SM-like Higgs boson mass in the MSSM, I will highlight some of the recent improvements in the effective field theory calculation that are relevant for multi-scale hierarchies. I.e., I will discuss the case of a heavy gluino as well as the case of light non-SM-like Higgs bosons (discussing also the effect of CP-violating phases).
We point out a novel role for the Standard Model neutrino in dark matter phenomenology where the exchange of neutrinos generates a long-range potential between dark matter particles. The resulting dark matter self interaction could be sufficiently strong to impact small-scale structure formation, without the need of any dark force carrier. This is a generic feature of theories where dark matter couples to the visible sector through the neutrino portal. It is highly testable with improved decay rate measurements at future Z, Higgs, and τ factories, as well as precision cosmology.
DEAP-3600 is a dark matter direct detection experiment running at the SNOLAB in Sudbury, Canada. The spherical detector is situated 2 km below the earth's surface with a low cosmic muon background environment consisting of 3.3 tonnes of liquid argon target surrounded by an array of 255 photomultiplier tubes. The major backgrounds for DEAP-3600 come from alpha particles induced by dust particles present inside the detector and detector components, from external neutrons, and from Argon-39 beta decays. In this talk, the latest results from DEAP-3600 and effort for the detailed background model, pulse-shape discrimination, and sensitivity of the dark matter will be presented. In addition, I will review ongoing R&D projects for hardware upgrades.
I will discuss the Higgs-portal dark matter scenario in the 5-dimensional brane world cosmology, such as Randall-Sundrum cosmology and Gauss-Bonnet cosmology.
We study for the first time the possibility of probing long-range fifth forces utilizing asteroid astrometric data, via the fifth force-induced orbital precession. We examine nine Near-Earth Object (NEO) asteroids whose orbital trajectories are accurately determined via optical and radar astrometry. Focusing on a Yukawa-type potential mediated by a new gauge field (dark photon) or a baryon-coupled scalar, we estimate the sensitivity reach for the fifth-force coupling strength and mediator mass in the mass range $m \simeq 10^{-21}-10^{-15}\,{\rm eV}$. Our estimated sensitivity is comparable to leading limits from torsion balance experiments, potentially exceeding these in a specific mass range. The fifth forced-induced precession increases with the orbital semi-major axis in the small $m$ limit, motivating the study of objects further away from the Sun. We discuss future exciting prospects for extending our study to more than a million asteroids (including NEOs, main-belt asteroids, Hildas, and Jupiter Trojans), as well as trans-Neptunian objects and exoplanets.
This talk is based on https://arxiv.org/abs/2107.04038.
In recent years, the usefulness of astrophysical objects as Dark Matter (DM) probes has become more and more evident, especially in view of null results from direct detection and particle production experiments. The potentially observable signatures of DM gravitationally trapped inside a star, or another compact astrophysical object, have been used to forecast stringent constraints on the nucleon-Dark Matter interaction cross section. Currently, the probes of interest are: at high red-shifts, Population III stars that form in isolation, or in small numbers, in very dense DM minihalos at $z\sim 15-40$, and, in our own Milky Way, neutron stars, white dwarfs, brown dwarfs, exoplanets, etc. Of those, only neutron stars are single-component objects, and, as such, they are the only objects for which the common assumption made in the literature of single-component capture, i.e. capture of DM by multiple scatterings with one single type of nucleus inside the object, is valid. In this paper, we present an extension of this formalism to multi-component objects and apply it to Pop III stars, thereby investigating the role of He on the capture rates of Pop III stars. As expected, we find that the inclusion of the heavier He nuclei leads to an enhancement of the overall capture rates, further improving the potential of Pop III stars as Dark Matter probes.
Multiple microlensing surveys have been conducted to place limits on primordial black holes in nearby dark matter halos. We show that these existing limits on PBHs can be recast to constrain dark matter lenses that are more spatially extended than PBHs. As two representative cases, we examine NFW subhalos and boson stars, which are predicted in many models such as axion miniclusters and axion stars. For the Subaru-HSC survey, the finite size of the source stars must also be considered. we find that the survey can probe NFW subhalos up to O(100) solar radii and boson stars up to O(1000) solar radii.
We discuss a systematic classification of the models with the minimal field content to account for, at the same time, the g-2 anomaly, the ones emerging in decays of B-mesons and, finally, a viable thermal Dark Matter. We will illustrate, in some specific examples, the strong complementarity among flavor and Dark Matter observables.
Scenarios in which right-handed light Standard Model fermions couple to a new gauge group, $U(1)_{T3R}$ can naturally generate a sub-GeV dark matter candidate. But such models necessarily have large couplings to the Standard Model, generally yielding tight experimental constraints.
We show that the contributions to $g_\mu-2$ from the dark photon and dark Higgs largely cancel out in the narrow window where all the experimental constraints are satisfied, leaving a net correction which is consistent with recent measurements from Fermilab.
These models inherently violate lepton universality, and UV completions of these models can include quark flavor violation which can explain $R_{K^{(\ast)}}$ anomalies as observed at the LHCb experiment after satisfying constraints on $Br(B_s\rightarrow\mu^+\mu^-)$ and various other constraints in the allowed parameter space of the model.
This scenario can be probed by FASER, SeaQuest, SHiP, LHCb, Belle, etc.
New light singlet scalars with flavor-specific couplings represent a phenomenologically distinctive and flavor-safe alternative to the well-studied possibility of Higgs-portal scalars. However, in contrast to the Higgs portal, flavor-specific couplings require an ultraviolet completion involving new heavy states charged under the Standard Model gauge symmetries, leading to a host of additional novel phenomena. Focusing for concreteness on a scenario with up quark-specific couplings, we investigate two simple renormalizable completions, one with an additional vector-like quark and another featuring an extra scalar doublet. We consider the implications of naturalness, flavor- and CP-violation, electroweak precision observables, and direct searches for the new states at the LHC. These bounds, while being model-dependent, are shown to probe interesting regions in the parameter space of the scalar mass and its low-energy effective coupling, complementing the essential phenomenology of the low-energy effective theory at a variety of low and medium energy experiments.
The confirmation of the discrepancy between the Muon g-2 experiment at Fermilab and the Standard Model prediction points to New Physics not far above the TeV scale. Flavour symmetries broken at low energies can account for it, although relevant constraints then arise from flavour-violating observables. Here I discuss the profound implications of this result over the structure of the charged-lepton mass matrix and apply these ideas to several discrete flavour groups popular in the lepton sector.
The Minimal R-symmetric Supersymmetric Standard Model possesses interesting features, which makes it an attractive alternative to the MSSM. Some of them can be observed in and are reflected by the lepton flavour violation processes. Notably, there is no $\tan\beta$-enhancement for $g-2$ of the muon and other dipole operators, resulting in very different predictions for lepton observables compared to the MSSM.
In the view of forthcoming experiments the bounds obtained from muon $g-2$ and flavour violating observables on the model parameter regions are studied. In particular, we consider the influence of Yukawa-like lambda parameters of the superpotential and the off-diagonal entries of slepton mass matrices. Different scenarios are discussed, depending also on the mass spectra of the model and additional restrictions, imposed by the anomalous magnetic moment of the muon. We focus on the interplay between $\mu\to e\gamma$, $\mu\to e$ conversion and $\mu\to 3e$ and $g-2$ of the muon and show that all of these observables are important to constrain the parameter space.
We explore the implications of g-2 new result to five models based on the SU(3)C×SU(3)L×U(1)N gauge symmetry and put our conclusions into perspective with LHC bounds. We show that previous conclusions found in the context of such models change if there are more than one heavy particle running in the loop. Moreover, having in mind the projected precision aimed by the g-2 experiment at FERMILAB, we place lower mass bounds on the particles that contribute to muon anomalous magnetic moment assuming the anomaly is resolved otherwise. Lastly, we discuss how these models could accommodate such anomaly in agreement with existing bounds.
Computing Donaldson-Thomas partition function of a G2 manifold has been a long standing problem. The key step for the problem is to understand the G2 instanton moduli space. I will discuss a string theory way to study the G2 instanton moduli space and explain how to compute the instanton partition function for a certain G2 manifold. An important insight comes from the twisted M-theory on the G2 manifold. This talk is based on a work in progress with Michele del Zotto and Yehao Zhou.
Pure spinor superfields provide a clean and powerful way of constructing and understanding supermultiplets, in any dimension and with any amount of supersymmetry, by using the algebraic geometry of the variety of square-zero elements in the corresponding supersymmetry algebra. This variety also classifies the possible twists of a supermultiplet. As such, it is natural to try and compute twists directly in a pure spinor superfield description. We show that this gives a general way of understanding the form of the twisted multiplets, which is related to the local geometry of the space of square-zero elements in the neighborhood of the twisting supercharge: in other words, the space of possible deformations of the selected twist to a further twist. The technique is efficient and requires essentially no detailed computations. Applications include new computations of the holomorphic twists of the eleven-dimensional and type IIB supergravity multiplets, verifying conjectures of Costello and Li.
A minimal model of $SU(5)$ Grand Unification is proposed. The model is entirely built out of the first five lowest dimensional $SU(5)$ representations. Charged and neutral fermion mass generation mechanisms are non-trivially linked together. The main predictions of the model are that $(i)$ the neutrinos are Majorana particles, $(ii)$ one neutrino is massless, $(iii)$ the neutrinos have normal mass ordering, and $(iv)$ there are four new scalar multiplets at or below a $120$TeV mass scale. An improvement of the current $p \rightarrow \pi^0 e^+$ lifetime limit by a factor of $2$, $15$, and $96$ would require these four scalar multiplets to reside at or below the $100$ TeV, $10$ TeV, and $1$ TeV mass scales, respectively.
We propose a $SU(5) \times U(1)_{PQ}$ Majoron-axion model free of the axion domain wall, axion dark matter isocurvature, and $SU(5)$ monopole problems. The vectorlike fermions in the model are essential to achieving successful unification of the SM gauge couplings as well as the viability of the inflation scenarios. The $SU(5)$ symmetry is broken at $M_{GUT} \simeq (4-7)\times 10^{15}$ GeV and the proton lifetime $\tau_p$ is estimated to be well within the expected sensitivity of the future Hyper-Kamiokande experiment, $\tau_p \lesssim 1.3 \times 10^{35}$ years. Meanwhile, the CASPEr experiment can search for the axion.
Abstract: In this talk I will present a model in which we minimally extend the Standard Model field content by adding new vector-like fermions at the TeV scale to allow gauge coupling unification at a realistic scale. We embed the model into a SU(5) GUT that is asymptotically safe and features an interacting fixed point for the gauge coupling. There are no Landau poles of the U(1) gauge and Higgs couplings. Gauge, Yukawa and Higgs couplings are retraced from the fixed point and matched at the GUT scale to those of the Standard Model rescaled up to the same energy. All couplings, their fixed point values and critical exponents always remain in the perturbative regime.
A new mechanism for the Higgs doublet being the light pseudo-Goldstone mode within SUSY SO(10) GUT will be presented.
Considered model exploits additional symmetries, which guarantee desirable symmetry breaking and natural all-order hierarchy. Some phenomenology, including a realistic fermion pattern, nucleon stability and gauge coupling unification, will be also discussed.
A 10 dimensional model with $\mathcal{N}=1$ SUSY and $E_8$ as a gauge symmetry will be presented. It will be shown that through the orbifold $\mathbb{𝑇}^6/(\mathbb{Z}_3\times\mathbb{z}_3$, only the Standard Model remains after compactification, with feasible Yukawa couplings. Gauge coupling unification can be achieved at energies as low as $M_{GUT}=10^7 GeV$ with a viable proton lifetime. Therefore the highly predictive extra dimensional GUT model can be within reach of near future experiments.
Ratios of nucleon decay rates between different channels can provide rich information about the specific GUT model realization in nature. To investigate this fingerprint in the context of SUSY GUTs and D=5 proton decay, we developed the software package SusyTCProton, which is an extension of the module SusyTC, itself to be used as a package of REAP. It takes the effective dimension 5 operators in the superpotential at the GUT scale as input, and assuming MSSM below the unification scale, computes the proton (neutron) partial decay rates into 7 (5) different decay channels.
We demonstrate the utility of this software on a pair of toy SUSY GUT models with different flavor structures. Performing a numerical fit and a subsequent MCMC analysis, we find that both models provide an equally good fit to the low energy data, while they differ in their prediction for nucleon decay fingerprints, making it possible, at least in principle, to experimentally distinguish between them.
The talk is based on 2011.15026 [hep-ph].
This talk reviews recent work done in collaboration with H. Jang on recently discovered new supergravity actions. Besides the standard ones, they contain new terms that become singular when auxiliary fields vanish. Constraints on the magnitude of such new terms are found by standard low-energy effective field theory consistency checks. After discussing those constraints I will present a realization of supergravity inflation that uses the new Kaehler-invariant Fayet-Iliopoulos term recently introduced by Antoniadis, Chatrabhuti, Isono and Knoops.
In the first part of the talk I will review the relation between the anomalies in six dimensions and the Chern-Simons couplings in five. These determine in particular the central charges of string-like BPS objects that cannot be consistently decoupled from gravity, a.k.a. supergravity strings. In the second part of the talk I will review how requiring that the worldsheet theory of the supergravity strings imposes bounds on the admissible theories of quantum gravity.
Type IIB supergravity famously has a discrete duality group, which is an exact symmetry of the full type IIB string theory. This symmetry has potential quantum anomalies, which could render the theory inconsistent. In this talk I will describe how we computed these anomalies in recent work, and show they are nonvanishing, but remarkably, they can be cancelled by a subtle modification of the IIB Chern-Simons term in what amounts to a new variant of the Green-Schwarz mechanism. This can only happen because of some "miraculous cancellations" that depend on the details of the IIB supergravity spectrum. I will also describe alternative ways to cancel this anomaly, presenting variant versions of IIB string theory which have the same IIB supergravity as the low-energy limit, but which differ at the nonperturbative level. These theories may or may not be in the Swampland.
Precision measurements and searches for new phenomena in the Higgs sector are among the most important goals in particle physics. Experiments at the Future Circular Colliders (FCC) are ideal to study these questions. Electron-positron collisions (FCC-ee) up to an energy of 365 GeV provide the ultimate precision with studies of Higgs boson couplings, mass, total width, and CP parameters, as well as searches for exotic and invisible decays. Very high energy proton-proton collision (up to 100 TeV) provided by the FCC-hh will allow studying the Higgs self-coupling. There is a remarkable complementarity of the FCC-ee and FCC-hh colliders, which in combination offer the best possible overall study of the Higgs boson properties.
As Higgs factory, Higgs study is one of the main physics goal at the CEPC. This presentation will present the latest Higgs results at CDR and new updates afterwards. In addition, the impact of 360 GeV run on CEPC Higgs physics will be addressed as well. Finally, some comparison with other colliders on physics will be discussed.
We propose a method to improve the efficiency of preselection in Higgs signal searches at CEPC.
For this propose we developed three machine learning algorithms including boosted decision tree algorithm, fully-connected neural networks and convolutional neural networks.
Among all these algorithms, we found the fully-connected neural networks gives the best prediction on Higgs signals.
Using such algorithms, we improve the signal strength of s-tagging events from cut-based result, $\mu_{ss} \sim 100$, to FCNN result $\mu_{ss} \sim 10$.
We consider scattering amplitudes in N=4 super Yang-Mills theory. Apart from any physics motivation about the exponentiation of infrared divergences, purely from the positive geometry of the loop Amplituhedron, we find that the logarithm of the amplitude appears as a natural object to look at. Thinking about `negative geometries' gives a useful decomposition of the latter, different from usual Feynman diagrams. We define a new observable that can be defined directly in terms of negative geometries, and integrated directly in four dimensions. Purely from the perspective of the geometry, there is a clear separation in the complexity of different contributions. We compute analytically a particular class of terms to all loop orders, and extract their contribution to the cusp anomalous dimension. We find that our analytic result reproduces several qualitative features of the full answer.
We analytically study the Fermi-gas formulation of sphere correlation functions of the Coulomb branch operators for 3d $\mathcal{N} = 4$ ADHM theory with a gauge group $U(N)$, an adjoint hypermultiplet and $l$ hypermultiplets which can describe a stack of $N$ M2-branes at $A_{l−1}$ singularities. We find that the leading coefficients of the perturbative grand canonical correlation functions are invariant under a hidden triality symmetry conjectured from the twisted M-theory. The triality symmetry also helps us to fix the next-to-leading corrections analytically.
In the past decade our understanding of scattering amplitudes in maximally supersymmetric Yang Mills theory has increased dramatically. This enhanced understanding has led to a formulation of color-ordered scattering amplitudes as logarithmic differential forms on particular geometries, called positive geometries. In particular, the momentum amplituhedron is the geometry governing the tree-level amplitudes in spinor helicity space, and it allows for considering different orderings. In this talk, I will review the construction of the momentum amplituhedron as well as discuss
some surprising recent results regarding how the Kleiss-Kuijf
relations arise geometrically in this framework.
We always have the freedom to reparametrize any QFT without affecting the underlying physics, but this freedom is not always manifest in the way we write it down. Vilkovisky demonstrated that the standard definition of the effective action yields different off-shell results for different parametrizations of the same theory. This issue is neatly resolved through the covariant Vilkovisky-De Witt (VDW) formalism, which offers a geometric interpretation of a QFT as a (pseudo)Riemannian manifold, in which the fields take on the role of coordinates. Reparametrizations are therefore realized through diffeomorphisms in this field-space manifold, which leave the physics manifestly invariant. However, the application of this covariant formalism to fermionic degrees of freedom and the proper definition of the fermionic field space metric have been elusive. In this talk, I will demonstrate how the VDW formalism can be extended to take into account both scalar and fermion fields. This is made possible by promoting the field space manifold to a supermanifold, which is equipped with a supermetric. In this way, the space of QFTs becomes fully geometrized, and every theory can be written in a manifestly reparametrization-invariant manner.
Local exact solutions for the scalar field theory, both for the classical and the quantum case have been recently obtained [1{3] by a technique devised by Bender, Savage and Milton [4]. This permits to derive the set of Dyson-Schwinger equations in a fully differential form. These methods can be applied also to the exact solution of the Yang-Mills theory [5] and corresponding confinement studies [6]. It is also possible to get a significant agreement for the spectrum of the theory [7] and to prove confinement in 2+1 dimensions [8].
Non-local quantum field theories have been studied recently as a promising approach to go beyond the Standard Model (e.g. see [9-11]). This approach is motivated by p-adic string field theory [12-14]. These theories have the properties of UV-completeness and have been proposed as a direction of UV-completion the non-local inifinte-derivative theories, and are ghost-free, re-normalizable and predicts conformal invariance at the quantum level [10, 15]. They are able to rescue dark matter models [11], move trans-planckian processes to sub-planckian [16] and improve inflationary behaviour of the Higgs field [17]. Along these same research avenues, we consider an infinite derivative non-local Yang-Mills theory and we show and we derive the set of Dyson-Schwinger equations in differential form till the 2P-correlation functions. Then, we provide a method to solve them, assuming that non-local effects are small at low-energies and taking into account only the leading order solutions [19] as we already show for the scalar field case [18]. The argument about confinement, put forward in [6], is then extended to this non local case [20]. It is seen that UV-limit is never reached in this case and the theory confines in the IR, the coupling running to infinity, without the appearance of a Landau pole. In these studies, we just assume that one has a proper local solutions to start from to get the corrections due to the non-locality. An immediate consequence of this approach is that the a mass gap is obtained and the spectrum of the theory becomes accessible analytically. In any case, the mass gap is diluted in the UV.
References
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[3] M. Frasca, Eur. Phys. J. Plus 131, no.6, 199 (2016) [arXiv:1504.02299 [hep-ph]].
[4] C. M. Bender, K. A. Milton and V. M. Savage, Phys. Rev. D 62, 085001 (2000) [hep-th/9907045].
[5] M. Frasca, Eur. Phys. J. Plus 132, no.1, 38 (2017) [erratum: Eur. Phys. J. Plus 132, no.5, 242 (2017)] [arXiv:1509.05292
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[10] A. Ghoshal, A. Mazumdar, N. Okada and D. Villalba, Phys. Rev. D 97, no.7, 076011 (2018) [arXiv:1709.09222 [hep-th]].
[11] A. Ghoshal, Int. J. Mod. Phys. A 34, no.24, 1950130 (2019) [arXiv:1812.02314 [hep-ph]].
[12] E. Witten, Nucl.Phys. B268, p. 253, (1986).
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[15] L. Buoninfante, G. Lambiase and A. Mazumdar, Nucl. Phys. B 944, 114646 (2019) [arXiv:1805.03559 [hep-th]].
[16] L. Buoninfante, A. Ghoshal, G. Lambiase and A. Mazumdar, Phys. Rev. D 99, no.4, 044032 (2019) [arXiv:1812.01441
[hep-th]].
[17] A. S. Koshelev and A. Tokareva, [arXiv:2006.06641 [hep-th]].
[18] M. Frasca and A. Ghoshal, [arXiv:2011.10586 [hep-th]], to appear in Classical and Quantum Gravity.
[19] M. Frasca and A. Ghoshal, [arXiv:2102.10665 [hep-th]], to appear in Journal of High-Energy Physics.
[20] M. Frasca, A. Ghoshal and N. Okada, [arXiv:2106.07629 [hep-th]].
Right-handed neutrinos appear in several extensions beyond the Standard Model, specially in connection to neutrino masses. Weak scale right-handed neutrino dark matter constructions are typically rather constrained by data. In this work, we carry out the dark matter phenomenology of a weak scale right-handed neutrino dark matter, within a type I seesaw model, in the presence of a fast early expansion of the universe (relentless production), and early matter-domination before or during dark matter freeze-out. We compute the dark matter relic density, the non-conventional direct detection rate featuring a spin-independent but velocity suppressed operator, and the existing collider bounds.
Axions, if they exist, can be produced efficiently in white dwarfs, free-stream out of the star due to their weak interactions with matter, and then be converted to a photon in the stellar magnetosphere. X-ray telescope observations of these stars can provide strong constraints on the coupling to electromagnetism and matter. I discuss the results of the first dedicated observation of a magnetic white dwarf in hard X-rays, and what it tells us about axions.
We present several models of asymmetric dark matter (ADM) and baryons coming from dark phase transitions and unique complementary signals. One achieves both baryogenesis and ADM in a minimal "mirror" sector, while another adds (heavy) ADM to any standard baryogenesis scenario. Yet another uses the most minimal dark sector to achieve baryogenesis alone. Thanks to the necessity of the vector and neutrino portals, discoverable signals include nuclear/electron recoils in direct detection experiments, visibly decaying dark photons, exotic Higgs and Z decays, extra relativistic degrees of freedom, and gravitational waves from the dark phase transition.
We perform the maximal twist of eleven-dimensional supergravity. This twist is partially topological and exists on manifolds of G2 × SU(2) holonomy. Our derivation starts with an explicit description of the Batalin-Vilkovisky complex associated to the three-form multiplet in the pure spinor superfield formalism. We then determine the L∞ module structure of the supersymmetry algebra on the component fields. We twist the theory by modifying the differential of the Batalin-Vilkovisky complex to incorporate the action of a scalar supercharge. We find that the resulting free twisted theory is given by the tensor product of the de Rham and Dolbeault complexes of the respective G2 and SU(2) holonomy manifolds as conjectured by Costello.
In this talk I explain how the maximal twist of eleven-dimensional supergravity in the free perturbative limit can be computed directly in the BV formalism. The maximal twist exists on manifolds of $G_2 \times SU(2)$ holonomy and is partially topological. After a short introduction to the BV formalism and twisting, I describe the $L_\infty$ action of the supersymmetry algebra on the component fields of the supergravity multiplet. Decomposing these transformations and the BV differential under $G_2 \times SU(2)$, the twisted theory can be identified. The result takes a simple form as conjectured by Costello. The talk is based on arxiv:2106.15640.
We propose a pseudo-Goldstone boson dark matter (pGDM) particle in $SO(10)$ grand unified theory (GUT). Due to its Goldstone nature, this pGDM evades the direct DM detection experiments which, otherwise, severely constrain the parameter space of DM models. In $SO(10)$, the pGDM is embedded as a linear combination of the Standard Model (SM) singlet scalars in ${\bf 16_H}$ and ${\bf 126_H}$ representations. We consider two scenarios for the intermediate route of $SO(10)$ symmetry breaking (SB) to the SM: $SU(5) \times U(1)_X$ and Pati-Salam the $SU(4)_c \times SU(2)_L \times SU(2)_R$ gauge groups. The vacuum expectation value of ${\bf 126_H}$, which triggers the breaking of $U(1)_X$ and 4-2-2 symmetry in the two scenarios, respectively, determines the pGDM lifetime whose astrophysical lower bound provides one of the most stringent constraints. The proton lifetime in the $SU(5)$ case is predicted to be $4.53 \times 10^{34}$ years, which lies well within the sensitivity reach of the Hyper-Kamiokande experiment.
Imposing the gauge coupling unification and the Higgsino-like neutralino dark matter in our Universe, we perform a parameter scan for a simple parameter set in the Minimal Supersymmetric Standard Model, namely, the universal sfermion mass ($m_0$) and the universal gaugino mass at the GUT scale ($M$). We find that sparticle masses in the range of 10-100 TeV result in the lifetime of proton decay mediated by the GUT gauge bosons that can be tested in the Hyper-Kamiokande experiment in the near future.
Attempts to account for the elementary properties of matter through a structure of extra spatial dimensions date from the theory of Kaluza 100 years ago. In more recent years, while there is still no clear evidence that extra dimensions of space exist, the origin of the structure of the Standard Model has become a central question in fundamental particle physics. We describe how a new approach, with a further generalisation from the local 4-dimensional spacetime geometry to a general form for proper time, leads directly and efficiently to Standard Model structures. This generalisation naturally makes use of unique mathematical structures involving the octonion algebra and the exceptional Lie groups that are also seen in some SUSY models. As an additional feature of the theory a natural candidate for dark matter, itself a further major mystery in physics, can also be directly identified.
The recent gravitational wave observations of the collision of black holes and neutron stars have allowed us to pierce into the extreme gravity regime, where gravity is simultaneously unfathomably large and wildly dynamical. These waves encode a trove of information about physics that is prime for the taking, including potential revelations about the validity of Einstein's theory and possible string-inspired extensions. In this talk, I will describe some of the physics inferences we have made from gravitational wave observations, and the future inferences that will comes next.
Gravitational waves produced by astrophysical sources and propagation through cosmic distances in inhomogeneous universe
In this talk, we shall present our recent studies of gravitational waves (GWs) first produced by remote compact astrophysical sources and then propagating in our inhomogeneous universe through cosmic distances, before arriving at detectors. To describe such GWs properly, we first introduce three scales,
$\lambda, \; L_c$ and $L$, denoting, respectively, the typical wavelength of GWs, the scale of the cosmological perturbations, and the size of the observable universe. For GWs to be detected by the current and foreseeable detectors, the condition $\lambda \ll L_c \ll L$ holds. Then, such GWs can be approximated as high-frequency GWs and be well separated from the background $\gamma_{\mu\nu}$ by averaging the spacetime curvatures over a scale $\ell$, where $\lambda \ll \ell \ll L_c $, and $g_{\mu\nu} = \gamma_{\mu\nu} + \epsilon h_{\mu\nu}$ with $\epsilon \simeq {\cal{O}}(\lambda/L)$, and $h_{\mu\nu}$ denotes the GWs. In order for the backreaction of the GWs to the background spacetimes to be negligible, we must assume that $\left|h_{\mu\nu}\right| \ll 1$, in addition to the condition $\epsilon \ll 1$, which are also the conditions for the linearized Einstein field equations for $h_{\mu\nu}$ to be valid. Such studies can be significantly simplified by properly choosing gauges, such as the spatial ($\chi_{0\mu} = 0$), traceless ($\gamma^{\mu\nu}\chi_{\mu\nu} = 0$), and Lorentz ($\nabla^{\nu}\chi_{\mu\nu}
= 0$) gauges, where $\chi_{\mu\nu} \equiv h_{\mu\nu} - h\gamma_{\mu\nu}/2$, and $\nabla^{\nu}$ denotes the covariant derivative with respect to $\gamma_{\mu\nu}$. We show that these three different gauge conditions can be imposed simultaneously, even when the background is not vacuum, as long as the high-frequency GW approximation is valid. However, to develop the formulas that can be applicable to as many cases as possible, we first write down explicitly the linearized Einstein field equations for $\chi_{\mu\nu}$ by imposing only the spatial gauge. Then, applying these formulas together with the geometrical optics approximation to such GWs, we find that they still move along null geodesics and its polarization bi-vector is parallel-transported, even when both the cosmological scalar and tensor perturbations are present. In addition, we also calculate the gravitational integrated Sachs-Wolfe effects due to these two kinds of perturbations, whereby the dependences of the amplitude, phase and luminosity
distance of the GWs on these perturbations are read out explicitly.
J. Fier, X.-J. Fang, B.-W. Li, S. Mukohyama, A. Wang, T. Zhu, Gravitational wave cosmology I: high frequency approximation, Phys. Rev. D (2021) [arXiv:2102.08968].
TBA
We study the minimal coupling of Chern-Simons gravity based on the Maxwell symmetry with massless spin-5/2 gauge fields, in three dimensions. It is shown the simplest hyper-Maxwell super-algebra and its corresponding Chern-Simons gravity, which contains a massless spin-2 fields which is coupled with a massless Majorana fermion spin-5/2. For certain combinations of osp(1/4) and sp(4) algebras, we find two different alternatives for hypersymmetric extensions of the Maxwell algebra, using the Inönü-Wigner contraction procedure. The hyper-Maxwell Chern-Simons actions was constructed for each case, which show interactions of non-propagating spin-4 fields with one or two spin-5/2 gauge fields.
I discuss the physics that underpins QED collinear-factorisation formulae, in particular the PDFs, and some applications of the latter to the simulation of e+e- collision processes
After the triumph of discovering the Higgs boson at the CERN Large Hadron Collider, people are getting increasingly interested in studying the Higgs properties in detail and searching for the physics beyond the Standard Model (SM). A multi-TeV lepton collider provides a clean experimental environment for both the Higgs precision measurements and the discovery of new particles. In high-energy leptonic collisions, the collinear splittings of the leptons and electroweak (EW) gauge bosons are the dominant phenomena, which could be well described by the parton picture. In the parton picture, all the SM particles should be treated as partons that radiated off the beam particles, and the electroweak parton distribution functions (EW PDFs) should be adopted as a proper description for partonic collisions of the initial states. In our work, both the EW and the QCD sectors are included in the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) formalism to perturbatively resum the potential large logarithms emerging from the initial-state radiation (ISR). I will show the results of QCD jet production as well as some other typical SM processes at a possible high-energy electron-positron collider and a possible high-energy muon collider obtained using the PDFs.
In this talk we first review the radiative seesaw scenario in the context of inverse seesaw models, in which small lepton number violating parameters generate radiatively at the one-loop order the observed small light neutrino masses. Then, we show how the supersymmetric version of this radiative mechanism offers cancellations among the one-loop contributions to neutrino masses thanks to a SUSY non-renormalization theorem, thereby relaxing dramatically the size of the lepton number violating parameters in such models. Finally, we discuss the phenomenological and cosmological implications of this radiative SUSY seesaw scenario.
In a seesaw scenario, GUT and family symmetry can severely constrain the structure of the Dirac and Majorana mass matrices of neutrinos. We will discuss an interesting case where these matrices are related in such a way that definite predictions for light neutrino masses are achieved without specifying the seesaw scale. This opens up the possibility to consider both high- and low-scale leptogenesis. We will explore both of these possibilities in an $SU(5)\times \mathcal{T}_{13}$ model and show that sub-GeV right-handed neutrinos with active-sterile mixing large enough to be probed by DUNE can explain baryon asymmetry of the Universe through resonant leptogenesis.
We consider light new particles $\chi$ and $\phi$ that carry baryon and lepton numbers. If these particles are lighter than nucleons they lead to exotic decays such as $p\to \pi^+ \chi$ and $p\to e^+\phi$, not yet fully constrained by dedicated searches. For $\chi$ and $\phi$ masses in the GeV range, proton decays are kinematically forbidden but other decays of the forms baryon\,$\to$\,meson$+\chi$, meson\,$\to$\,baryon$+\bar\chi$, and baryon\,$\to$\,anti-lepton$+\phi$ involving heavy initial hadrons are allowed. This opens up the possibility to search for apparent baryon number violation not just in underground experiments such as Super-Kamiokande and DUNE but also in decays of heavy hadrons in charm and $B$ factories.
The NA62 experiment at CERN reports searches for K+ → e+N, K+→μ+N and K+→μ+νX decays, where N and X are massive invisible particles, using the 2016-2018 data set.
The N particle is assumed to be a heavy neutral lepton, and the results are expressed as