Jun 14 – 18, 2021
Asia/Seoul timezone

Abstracts - Particle Physics

ALBERT, Andreas Boston University Title: Searches for Dark Matter at CMS
Over the last decades, cosmological evidence has amassed suggesting the existence of a novel form of "dark" matter. The question of its origin and possible particle nature are at the forefront of physics research today. If dark matter were indeed made of new particles, it could be produced in collisions of known particles at colliders. At the CERN LHC, large samples of proton-proton collisions at the unprecedented center-of-mass energy of 13 TeV have been generated in the second data-taking period between 2015 and 2018. The CMS collaboration, which operates a large general-purpose detector system to observe these collisions with great precision, has recorded a data set corresponding to an integrated luminosity of 137 inverse femtobarns during this time. The analysis of this giant data set provides a uniquely sensitive tool to search for collider production of potential dark matter particles.
BARREIROS, Débora CFTP/IST, U. Lisboa Title: Neutrino masses from simple scoto-seesaw model with spontaneous CP violation
Abstract: I will discuss our recent work on a simple scoto-seesaw model that accounts for dark matter and neutrino masses with spontaneous CP violation. This is achieved with a single horizontal Z8 discrete symmetry, broken to a residual Z2 subgroup responsible for stabilizing dark matter. CP is broken spontaneously via the complex vacuum expectation value of a scalar singlet, inducing leptonic CP-violating effects. We find that the imposed Z8 symmetry pushes the values of the Dirac CP phase and the lightest neutrino mass to ranges already probed by ongoing experiments.
BRENNER, Lydia CERN Title: The new FASER experiment at the CERN LHC.
The FASER experiment is a new small and inexpensive experiment that is being placed 480 meters downstream of the ATLAS experiment at the CERN LHC. The experiment will shed light on currently unexplored phenomena, having the potential to make a revolutionary discovery. FASER is designed to capture decays of exotic particles, produced in the very forward region, out of the ATLAS detector acceptance. This talk will present the physics prospects, the detector design, and the construction progress of FASER. The experiment has been successfully installed and will take data during the LHC Run-3.
CHONGDAR, Sreerupa National Institute of Technology, Rourkela Title: Flavoured leptogenesis and type-II seesaw mechanism with two Higgs triplet scalars
Type-II seesaw mechanism has been widely studied already as the link between neutrino mass generation beyond Standard Model (SM) and leptogenesis. In this study, the SM is minimally extended by two triplet Higgs scalars (with hypercharge $Y=2$), with one triplet having complex vacuum expectation value (vev) to impose generality. The triplet vevs are bounded by the $\rho$-parameter constraint as, $\omega_{1}$, $\omega_{2}\ll v$, where $v$ is the vev of the SM Higgs doublet. The neutrino mass gets generated by two massive triplet Higgs, without any right-handed neutrino in this model. On the other hand, purely flavoured leptogenesis is achieved when the triplet Higgs scalar of mass $M_{T}\sim10^{9}$ GeV, undergoes out-of-equilibrium bi-lepton decay, specially through lepton loop. The lepton asymmetries further get converted into baryon asymmetry via nonperturbative sphaleron process. This study shows the efficiency of phenomenologically promising type-II seesaw mechanism with two triplet scalars, in order to estimate the baryon asymmetry through fully flavoured leptogenesis. Here, baryon asymmetry of the order $\sim 10^{-10}$ is achieved through the stated model, which falls within the experimentally obtained range. The dependence of the baryon asymmetry on the branching ratios of triplet scalar is also studied here. To further increase the predictability of the mechanism, two-zero texture- $B_{2}$ is introduced in the neutrino mass matrix. The neutrino mass matrix elements are bounded by the latest neutrino oscillation parameter data and the sum of neutrino mass is taken to be $\Sigma_{i} m_{i}<0.16$ eV. The efficacy of two-zero texture $B_{2}$ in two Higgs triplet scenario is mentioned.
CORREIA, Fagner Korea Institute for Advanced Study Title: Probing Leptophobic $U(1)_H$ Theories at the J-PARC KOTO
Abstract: $K_L \to \pi \nu \nu $ is one of the attractive processes to test new physics beyond the Standard Model (SM). It is drawing attention, thanks to the effort of the KOTO collaboration. In this talk, we briefly study the $K_L$ decay and other relevant flavor violating processes in a class of type-II two Higgs doublet models with extra gauged $U(1)_H$ symmetry. We sort few examples where the source of missing energy in Kaon decays is given by either dark bosons or massive neutrinos. We focus on the setup where effects of the extra gauge boson, $Z_H$ and of pseudoscalar portals will emerge primarily at the electroweak penguin level of $\Delta F = 1,2$ processes. We show that J-PARC KOTO most stringent upper limit for the branching ratio of $K_L \to \pi \nu \nu $ leads to important bounds for leptophobic and multi-Higgs $SM \otimes U(1)_X$ theories, at or below the electroweak scale, comparable to the limits provided by hadron colliders.
DENTON, Peter Brookhaven National Lab Title: CP-Violating Neutrino Non-Standard Interactions in Long-Baseline-Accelerator
Neutrino oscillations in matter provide a unique probe of new physics. Leveraging the advent of neutrino appearance data from NOvA and T2K in recent years, we investigate the presence of CP-violating neutrino non-standard interactions in the oscillation data. We first show how to very simply approximate the expected NSI parameters to resolve differences between two long-baseline appearance experiments analytically. Then, by combining recent NOvA and T2K data, we find a tantalizing hint of CP-violating NSI preferring a new complex phase that is close to maximal: $\phi_{e\mu}$ or $\phi_{e\tau}\approx3\pi/2$ with $|\epsilon_{e\mu}|$ or $|\epsilon_{e\tau}\sim0.2$. We then compare the results from long-baseline data to constraints from IceCube and COHERENT.
DUTTA, MANORANJAN Indian Institute of Technology Hyderabad Title: Self-interacting Inelastic Dark Matter in the Light of XENON1T Excess:
We propose a self-interacting inelastic dark matter (DM) scenario as a possible origin of the recently reported excess of electron recoil events by the XENON1T experiment. Two quasi-degenerate Majorana fermion DM interact within themselves via a light hidden sector massive gauge boson and with the standard model particles via gauge kinetic mixing. We also consider an additional long-lived singlet scalar which helps in realising correct dark matter relic abundance via a hybrid setup comprising of both freeze-in and freeze-out mechanisms. While being consistent with the required DM phenomenology along with sufficient self-interactions to address the small scale issues of cold dark matter, the model with GeV scale DM can explain the XENON1T excess via inelastic down scattering of heavier DM component into the lighter one. All these requirements leave a very tiny parameter space keeping the model very predictive for near future experiments.
FELKL, Tobias University of New South Wales Title: The Singly-Charged Scalar Singlet as the Origin of Neutrino Masses
We consider the generation of neutrino masses via a singly-charged scalar singlet. Under general assumptions we identify two distinct structures for the neutrino mass matrix. This yields a constraint for the antisymmetric Yukawa coupling of the singly-charged scalar singlet to two left-handed lepton doublets, irrespective of how the breaking of lepton-number conservation is achieved. The constraint disfavours large hierarchies among the Yukawa couplings. We study the implications for the phenomenology of lepton-flavour universality, measurements of the W-boson mass, flavour violation in the charged-lepton sector and decays of the singly-charged scalar singlet. We also discuss the parameter space that can address the Cabibbo Angle Anomaly.
FORNAL, Bartosz University of Utah Title: Probing Baryonic Dark Matter Models with Gravitational Waves
Gravitational waves provide a unique method of testing theories with extended gauge symmetries. In particular, spontaneous symmetry breaking can lead to a detectable stochastic gravitational wave background generated by cosmic strings and first order phase transitions in the early universe. I will discuss the unique gravitational wave signature of a simple model with gauged baryon and lepton numbers, in which a high scale of lepton number breaking is motivated by the seesaw mechanism for the neutrinos, whereas a low scale of baryon number breaking is required by the observed dark matter relic density. This novel signature can be searched for in near-future gravitational wave experiments.
FU, Bowen University of Southampton Title: Dark Matter in the Type Ib Seesaw Model
We study the connection between the two indications of physics beyond the Standard Model (SM): the masses and mixing of neutrinos and the existence of dark matter (DM). To have a more testable connection, we consider a minimal type Ib seesaw model instead of the traditional type I seesaw model. In the minimal type Ib seesaw model, the effective neutrino mass operator involves two different Higgs doublets and two right-handed neutrinos which form a single heavy Dirac pair. To account for DM, we consider neutrino portal couplings to a dark fermion and a dark scalar. We explore the parameter space of the extended model consistent with both oscillation data and DM relic abundance. Within this framework, we show how DM can be directly related to laboratory experiments when the heavy Diracneutrino mass is around 1~100 GeV.

Keywords: Comsology, High Energy Phenomenology
FUJIWARA, Motoko Nagoya University Title: A model of electroweakly interacting non-abelian vector dark matter
In this talk, we propose a new electroweakly interacting spin-1 dark matter (DM) model. We consider the non-Abelian extension of electroweak symmetry. Namely, we extend the SU(2)$_L$ group in the Standard Model (SM) into the direct products of three SU(2) groups. We also impose the exchange symmetry between two of these SU(2) groups to realize the spin-1 stable spectrum. In this setup, the DM pair efficiently annihilate into SM particles through the electroweak interaction. Therefore, we can obtain the DM energy density correctly via the freeze-out mechanism. We also find not only electroweak processes but also Higgs exchange processes give the relevant contribution to determine the DM energy density. We conclude a next-generation DM searches will be an excellent probe of this spin-1 DM. [keywords: High Energy Theory]
GANGULY, Joy Indian Institute of Technology Hyderabad Title: Neutrino mixing by modifying the Yukawa coupling structure of constrained sequential dominance
In the constrained sequential dominance (CSD), tri-bimaximal mixing (TBM) pattern in the neutrino sector has been explained, by proposing a certain Yukawa coupling structure for the right-handed neutrinos of the model. However, from the current experimental data it is known that the values of neutrino mixing angles are deviated from the TBM values. In order to explain this neutrino mixing, we first propose a phenomenological model where we consider Yukawa couplings which are modified from that of CSD. Essentially, we add small complex parameters to the Yukawa couplings of CSD. Using these modified Yukawa couplings, we demonstrate that neutrino mixing angles can deviate from their TBM values. We also construct a model, based on a flavor symmetry, in order to justify the modified form of Yukawa couplings of our work.
GEHRLEIN, Julia Brookhaven National Laboratory Title: Leptonic Sum Rules from Flavour Models with Modular Symmetries
Abstract: Sum rules in the lepton sector provide an extremely valuable tool to classify flavour models in terms of relations between neutrino masses and mixing parameters testable in a plethora of experiments. In this manuscript we identify new leptonic sum rules arising in models with modular symmetries with residual symmetries. These models simultaneously present neutrino mass sum rules, involving masses and Majorana phases, and mixing sum rules, connecting the mixing angles and the Dirac CP-violating phase. The simultaneous appearance of both types of sum rules leads to some non-trivial interplay, for instance,the allowed absolute neutrino mass scale exhibits a dependence on the Dirac CP-violating phase. We derive analytical expressions for these novel sum rules and present their allowed parameter ranges as well as their predictions at upcoming neutrino experiments.
HA, Taewook Korea University Title: Factorization for the N-jettiness in electroweak processes
We demonstrate the factorization theorem for 2→2 electroweak process at high energy. As a simple example, we consider e^+ e^-→μ^+ μ^-. Electrons emit initial state radiations (beams), daughter leptons get involved in hard scattering. After that, final state radiation also arises as muons or jets including a muon. The scattering cross section at energies much above the electroweak scale include electroweak large logarithms. They are already relevant for LHC analyses in TeV region and will become more important at future lepton colliders. In contrast to QCD, where all states are in color singlets, electroweak processes contain not only electroweak singlets, but also electroweak nonsinglets. Existence of nonsinglet states make the study more difficult.
Effective field theories are a useful tool to study the physics at various scales. We use the soft-collinear effective theory describing the interactions of the soft and collinear degrees of freedom. We will introduce the concepts and applications of the soft collinear effective theory briefly. After that, We show e^+ e^- →μ^+ μ^- universal factorization formula with the event shape N-jettiness, which constrains the N-signal jets. In the case that all of the factorized parts are singlets, our factorization formula is the same as the QCD factorization formula of qq ̅→q'(q') ̅. In addition, electroweak nonsinglets are involved in the factorization theorem. Brief explanation of each factorized function will be provided.
HERMS, Johannes Max-Planck-Institut für Kernphysik Title: Multi-flavour thermal relic dark matter
Standard Model fermions come in multiple generations, and so might dark matter particles. In this talk, we explore effects of the presence of multiple dark matter flavours on thermal relic production and signatures. For concreteness, we focus on a scenario with two flavours of dark matter fermions coupled to the SM leptons through a charged scalar mediator. We characterize the possible production regimes and identify cases where the heaver DM generation is crucial to obtaining the correct relic abundance, resulting in boosted indirect and direct detection signals, next to characteristic signatures of decay of the heavier dark matter generation to the lighter.
HONG, Deog Ki Pusan National University Title: Parity violation and new physics in superconductors
We propose a new method, using the Andreev reflection at superconductors, to measure parity violation induced by the standard electroweak theory, which in turn constrains the possible parity-violating effects of new physics. The weak neutral currents induce parity-violating, marginal effective operators, though quite tiny, in superconductors. We estimate their effects on superconducting gaps and propose a method to measure the parity-violation from the spin polarization effect, when electrons or holes get Andreev-reflected at the interface between normal metal and a superconductor. Such polarization effects might be comparable to the atomic parity violation and thus naturally give an interesting bound on certain models of new physics, that couples to electrons, such as Majorana mass of active neutrinos or doubly charged Higgs.
HUANG, Fa Peng Sun Yat-sen University (Zhuhai Campus) Title: Exploring the light dark matter by SKA
Motivated by the current status of dark matter direct search, we study new approaches to detect the light dark matter by SKA-like experiments.
JUEID, Adil Konkuk University Title: Minimal Leptophilic Dark Matter: Colliders and Beyond
In this talk, we discuss a new minimal model for GeV-scale Majorana dark matter (DM) coupled to the standard model lepton sector via a charged scalar singlet. The theoretical framework extends the Standard Model by two 𝑆𝑈(2)𝐿 singlets: one charged Higgs boson and a singlet right-handed fermion. The latter plays the role of the DM candidate. We show that there is an anti-correlation between the spin-independent DM-Nucleus scattering cross-section 𝜎SI and the DM relic density for parameter values allowed by various theoretical and experimental constraints. Moreover, we find that even when DM couplings are of order unity, 𝜎SI is below the current experimental bound but above the neutrino floor. Furthermore, we show that the considered model can be probed at High Energy lepton colliders using e.g. the mono-Higgs production and same-sign charged Higgs pair production while hadron colliders provide an extra complementary role. We discuss the potential of embedding this model into grand-unified theories and comment on the astrophysical implications.
KANG, Sunghyun Sogang University Title: WimPyDD : An object-oriented Python code to calculate WIMP direct detection signals
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.
KAWAMURA, Junichiro IBS-CTPU Title: ≥4μ signal from a vector-like lepton decaying to a muon-philic Z′ boson at the LHC
Abstract: We propose a novel possibility to detect a very distinctive signal with more than four muons originating from pair-produced vector-like leptons decaying to a muon-philic Z′ boson. These new particles are good candidates to explain the anomalies in the muon anomalous magnetic moment and the b→sℓℓ processes. The doublet (singlet) vector-like leptons lighter than 1.3 (1.0) TeV are excluded by the latest data at the LHC if BR(E→Z′μ)=1. We also show that the excess in the signal region with more than five leptons can be explained by this scenario if the vector-like lepton is a weak singlet, with mass about 400 GeV and BR(E→Z′μ)=0.25. The future prospects at the HL-LHC are discussed.
KAY, Ellis University of Victoria Title: Exploring the dark sector with the ATLAS detector
The presence of a non-baryonic Dark Matter component in the Universe is inferred from the observation of its gravitational interaction. If Dark Matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates, including resonance searches for the mediator which would couple DM to the SM as well as searches with large missing transverse momentum produced in association with other particles (quarks, photons, Z and H bosons) called mono-X searches and searches where the Higgs boson provides a portal to Dark Matter, leading to invisible Higgs decays. In the latter case, ATLAS also explores dark sector models where the Higgs boson can decay into a photon and an invisible dark photon. Furthermore, new particles with macroscopic lifetimes arise naturally in many beyond-the-standard-model scenarios. Long-lived particles are predicted in e.g. hidden valley models that include long lived mediators that decay to SM particles that leave striking and challenging signatures in the detector and maybe key to understanding naturalness and dark matter, and other outstanding questions in particle physics. The results of recent dark sector searches on 13 TeV pp data, their interplay and interpretation will be presented.
KO, Young Ju Institute for Basic Science Title: Dark matter search in the COSINE-100 experiment
Although there is evidence for the existence of dark matter in astrophysical observations, no direct detection has been reported except for claims of the DAMA/LIBRA collaboration. COSINE-100 experiment has been operating since September 2016 aiming to reproduce the DAMA/LIBRA annual modulation signal. The target material is NaI(Tl) crystal, as in the DAMA/LIBRA experiment. Data is being taken at the 700-m-deep Yangyang underground laboratory, Korea. In addition to the analysis of the annual modulation signal, interpretations based on various models have also been performed. With the recent successful lowering of the energy threshold from 2 keV to 1 keV, a new analysis is ongoing and near completion. In this presentation, we present an introduction of the experiment and the latest analysis results, as well as show the plans for the next phase, after validation of the DAMA/LIBRA's result.
KWON, Taehyun Korea university Title: Semi inclusive leptonic jet function in SU(2)_L
At extremely high energy large enough to ignore all electroweak particle masses, the leptons in the final state can make a jet. This electroweak jet is different from a QCD jet. Particles in electroweak jet cannot only be a gauge singlet, but also a gauge nonsinglet while particles in QCD jet should be a form of hadron, that is a color singlet. The existence of the gauge nonsinglet makes jet analysis more complicated.
We study lepton jets with small 2-jettiness in the process, e^+ e^- →J_(μ^+) J_(μ^-)+X where X means soft particles and J_l is a jet including the collinear lepton l in the final state. When there are only two jets, 2-jettiness is much smaller than 1. For simplicity, we will be considering only the SU(2)_w gauge interaction. Using Soft Collinear Effective Theory, the cross section is factorized by a hard function, two beam functions, two semi-inclusive jet functions (or fragmenting jet functions), and soft function.
We will compute semi-inclusive jet function and fragmenting jet function. Since the functions can come from nonsinglets, these have different divergences structures which cannot be observed in QCD jet function. We calculate these functions at 1-loop order, and resum them at next-to-leading logarithmic accuracy.
LONGO, Savino DESY Title: Dark-sector physics at Belle II
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.
LU, Chih-Ting KIAS Title: Shedding light on dark matter with recent muon (g−2) and Higgs exotic decay measurements
Recently, we have witnessed two hints of physics beyond the standard model: A 3.3$\sigma$ local excess ($M_{A_0} = 52$~GeV) in the search for $H_0\to A_0 A_0\to b\overline{b}\mu^{+}\mu^{-}$ and a 4.2$\sigma$ deviation from the SM prediction in the $(g-2)_\mu$ measurement.
The first excess was found by the ATLAS Collaboration using 139~fb$^{-1}$ data at $\sqrt{s}=13$~TeV\@. The second deviation is a combination of the results from the Brookhaven E821 and the recently reported Fermilab E989 experiment. We attempt to explain these deviations in terms of a renormalizable simplified dark matter model. Inspired by the null signal result from dark matter (DM) direct detection, we interpret the possible new particle, $A_0$, as a pseudoscalar mediator connecting DM and the standard model. On the other hand, a new vector-like muon lepton can explain these two excesses at the same time while contributing to the DM phenomenology.
MAHAPATRA, SATYABRATA INDIAN INSTITUTE OF TECHNOLOGY, HYDERABAD Title: Muon $(g-2)$ and XENON1T Excess with Dark Matter in $L_{\mu}-L_{\tau}$ Model
Motivated by the growing evidence for lepton flavour universality violation after the first results from Fermilab's muon $(g-2)$ measurement, we revisit one of the most widely studied anomaly free extensions of the standard model namely, gauged $L_{\mu}-L_{\tau}$ model, known to be providing a natural explanation for muon $(g-2)$. We also incorporate the presence of dark matter (DM) in this model in order to explain the recently reported electron recoil excess by the XENON1T collaboration. We show that the same neutral gauge boson responsible for generating the required muon $(g-2)$ can also mediate interactions between electron and dark matter. We consider two scenarios to explain the XENON1T excess; one with dark fermions boosted by DM annihilation and the other with inelastic down scattering of DM. In the former case, the required DM annihilation rate into dark fermion require a hybrid setup of thermal and non-thermal mechanisms to generate DM relic density. In the later case, a Dirac fermion DM, naturally stabilised due to its chosen gauge charge, is split into two pseudo-Dirac mass eigenstates due to Majorana mass term induced by singlet scalar which also takes part in generating right handed neutrino masses responsible for type I seesaw origin of light neutrino masses. The inelastic down scattering of heavier DM component can give rise to the XENON1T excess for keV scale mass splitting with lighter DM component. We fit our model with XENON1T data for both the cases and also find the final parameter space by using bounds from $(g-2)_{\mu}$, DM relic, lifetime of heavier DM, DM-electron scattering rate, neutrino trident production rate as well as other flavour physics, astrophysical and cosmological observations. The tightly constrained parameter space from all requirements remain sensitive to ongoing and near future experiments, keeping the scenario very predictive.
MASTROTOTARO, Leonardo Università degli Studi di Salerno Title: Massive sterile neutrinos in the Early Universe: from thermal decoupling to cosmological constraints
We consider heavy sterile neutrinos $\nu_s$ with mass in the range 10 MeV≤m_s≤m_π∼135 MeV, which are thermally produced in the Early Universe, in collisional processes involving active neutrinos, and freezing out after the QCD phase transition. Notably, if these neutrinos decay after the active neutrino decoupling, they generate extra neutrino radiation and contribute to entropy production: they alter the value of the effective number of neutrino species N_{eff} and ^4He production. We provide a detailed account of the numerical solution of the exact relevant Boltzmann equations. Finally, we also identify the parameter space allowed by current Planck satellite data and forecast the parameter space probed by future Stage-4 ground-based CMB observations, expected to match or surpass BBN sensitivity, improving the existing constraints on the sterile neutrino parameter space in both cases.
This talk is based on arXiv:2104.11752, work in collaboration with Pasquale Serpico, Alessandro Mirizzi e Ninetta Saviano.
NAKAGAWA, Shota Tohoku University Title: Non-thermally trapped inflation due to the tachyonic instability
The motion of the axion field explosively produces hidden photons due to the tachyonic instability. We consider the Abelian Higgs model coupled to the hidden photon which leads to the effective mass of the Higgs. When the axion starts to oscillate and the hidden photon are produced, the Higgs is trapped by the effective mass. If the vacuum energy of the Higgs dominates the universe, then the inflation non-thermally occurs in the late-time universe. In this talk, we will present our results and its implication for cosmology.
NAKAI, Yuichiro T. D. Lee Institute, Shanghai Title: Axion Quality from Superconformal Dynamics
We discuss a possibility that a superconformal dynamics induces the emergence of a global U(1)PQ symmetry to solve the strong CP problem through the axion. Fields spontaneously breaking the U(1)PQ symmetry couple to new quarks charged under the ordinary color SU(3)C and a new SU(N) gauge group. The theory flows into an IR fixed point where the U(1)PQ breaking fields hold a large anomalous dimension leading to the suppression of U(1)PQ -violating higher dimensional operators. The spontaneous breaking of the U(1)PQ makes the new quarks massive. The U(1)PQ symmetry is anomalous under the SU(3)C but not under the SU(N) so that the axion couples to only the color SU(3)C and the usual axion potential is generated. We also comment on a model that the U(1)PQ breaking fields are realized as meson superfields in a new supersymmetric QCD.
NOVICHKOV, Pavel SISSA/INFN Title: Lepton Mass and Mixing Patterns from Residual Modular Symmetries
Authors: Pavel Novichkov, João Penedo, Serguey Petcov
Keywords: High Energy Theory, String and Field
Abstract: In modular-invariant models of flavor, hierarchical charged lepton mass matrices may arise due to the proximity of the modulus $\tau$ to a residual symmetry point. We systematically go through the possible lepton field representation choices which may yield hierarchical structures in the vicinity of symmetric points, for the four smallest finite modular groups, isomorphic to $S_3$ and double covers of $A_4$, $S_4$, and $A_5$. After formulating the conditions for obtaining a viable lepton mixing matrix in the symmetric limit, we construct a model in which both the charged-lepton and neutrino sectors are free from fine-tuning.
PALACINO, Gabriel Indiana University Title: Searches for Higgs boson pair production with the full LHC Run-2 dataset in ATLAS
The latest results on the production of Higgs boson pairs (HH) in the ATLAS experiment are reported, with emphasis on searches based on the full LHC Run 2 dataset at 13 TeV. In the case of non-resonant HH searches, results are interpreted both in terms of sensitivity to the Standard Model and as limits on kappa_lambda, i.e. a modifier of the Higgs boson self-coupling strength. Searches for new resonances decaying into pairs of Higgs bosons are also reported.
PINFOLD , James University of Alberta Title: Results and future plans of the MoEDAL experiment
The unprecedented collision energy of the LHC has opened up a new discovery frontier, yet signs of new physics are yet to be seen. Such theories may be revealed in the lifetime frontier, which the MoEDAL detectors, specialised in magnetic monopoles and other highly ionising particles, are being exploring. Moreover, the planned MAPP detectors will probe the highly penetrating regime of new particles predicted in dark matter and other models. Further, a possible astroparticle extension to MoEDAL, called Cosmic-MoEDAL, will allow the search for magnetic monopoles to be continued from the TeV scale to the GUT scale. The presentation focuses on recent results and plans for the LHC Run 3.
ROUT, Prasant Kumar SAHA INSTITUTE OF NUCLEAR PHYSICS Title: Searches for BSM Higgs at CMS
The standard model Higgs boson has been already discovered at a mass of 125 GeV. However, it may not be the only Higgs boson in nature, many beyond-the-standard-model (BSM) theories such as two-Higgs-doublet models and next-to-Minimal-supersymmetric standard model predict extended Higgs sectors for the existence of neutral and charged Higgs bosons.
In the Run-II period of LHC, CMS experiment has collected a pretty large volume of data (137 inverse-femtobarn) than the Run-I period and hence enhanced the opportunity to explore the parameter space of the extended Higgs sectors in more detail.
In this talk, I will present the latest results of few BSM Higgs searches that has been carried out using the 2016 or full Run-II dataset in the CMS experiment at LHC.
SÁNCHEZ VILLAMIZAR, Yoxara Universidade Federal do Rio Grande do Norte Title: implications of the muon anomalous magnetic moment for the 3-3-1 models
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.
SHARMA, Varun University of Wisconsin - Madison Title: Searches for Lepton Number Violation at CMS
Searches for the charged lepton flavor violating processes have a long history, and their importance stems from their potential to probe physics higher than the TeV scale. The Higgs boson's small natural width easily accommodates interactions with previously undiscovered physics sectors, making the search for exotic decays associated with a Higgs boson a rich phenomenological territory to explore. Some beyond the standard model theories allow for lepton flavor violating decays of the Higgs boson, and observing such decays will be a clear sign of new physics. Several new scenarios have been studied using the full Run-2 data collected at the CMS experiment. These search results are expressed as the upper limits on the branching fraction of the Higgs or new heavy boson decaying into these final states. They are correspondingly translated into limits on the Yukawa couplings. The various analysis techniques involved in the analysis and the results will be presented in the talk.
SINGH, Rajeev Institute of Nuclear Physics Polish Academy of Sciences Title: Quantum fluctuations of energy in a hot relativistic gas of fermions. (High Energy Theory/Nuclear Theory)
Abstract: Expressions for quantum fluctuations of energy in subsystems of a hot relativistic gas of fermions are derived where the results depend on the form of the energy-momentum tensor, which is a property dependent on pseudo-gauge. We find for sufficiently large subsystems the results obtained in different pseudo-gauges converge and hence, agree with the canonical-ensemble formula known from statistical physics. As different forms of the energy-momentum tensor of a gas are a priori equivalent, our finding suggests that the concept of quantum fluctuations of energy in very small thermodynamic systems is pseudo-gauge dependent. On the practical side, the results of our calculations determine a scale of coarse graining for which the choice of the pseudo-gauge becomes irrelevant.
SONG, Ji Seon Chung-Ang University Title: Flux-mediated Dark Matter
We propose a new mechanism to communicate between fermion dark matter and the Standard Model (SM) only through the four-form flux. The four-form couplings are responsible for the relaxation of the Higgs mass to the correct value and the initial displacement of the reheating pseudo-scalar field from the minimum. We show that the simultaneous presence of the pseudo-scalar coupling to fermion dark matter and the flux-induced Higgs mixing gives rise to unsuppressed annihilations of dark matter into the SM particles at present, whereas the direct detection bounds from XENON1T can be avoided. We suggest exploring the interesting bulk parameter space of the model for which dark matter annihilates dominantly into a pair of singlet-like scalars with similar mass as for dark matter.
TOMAR, Dr. Gaurav Technical University of Munich Title: Impact of operators interference in dark matter direct detection experiments
The non-relativistic effective theory of WIMP-nucleon interactions depends on 28 coupling strengths for a WIMP particle with spin up to 1/2. Due to the vast parameter space of the effective theory, most direct detection experiments interpret the results of their searches assuming that only one of the coupling strengths is non-zero. On the other hand, dark matter models generically lead in the non-relativistic limit to several interactions which interfere with one another, therefore, the published limits cannot be straightforwardly applied to model predictions. We present a method to determine a rigorous upper limit on the WIMP-nucleon interaction strength including all possible interferences among operators. We illustrate the method using the null search results from the XENON1T and the PICO collaborations; for some interactions, the limits on the coupling strengths are relaxed up to one order of magnitude. We also present a method that allows to combine the results from different experiments, thus exploiting the synergy between different targets in exploring the parameter space of WIMP-nucleon interactions.
VALLI, Mauro U.C. Irvine TITLE: Gamma Factory Searches for Extremely Weakly-Interacting Particles
The Gamma Factory is a recent proposal to back-scatter laser photons off a beam of partially-stripped ions at the LHC, yielding ∼ 10 MeV to 1 GeV photons with intensities of 10^16 to 10^18 s−1. In this talk I will
discuss the discovery potential of new weakly-interacting particles at this factory via “dark Compton scattering”. I will highlight the opportunity of discovering extremely weakly-interacting particles with just a few hours of data and stress the complementarity to astrophysical probes. I will outline the requirements of an experiment to realize this potential and the sensitivity reach for various experimental configurations.
YAMASHITA, Kimiko IHEP, CAS Title: Elastic positivity vs extremal positivity bounds in SMEFT: a case study in transversal electroweak gauge-boson scatterings
The positivity bounds, derived from the axiomatic principles of quantum field theory (QFT), constrain the signs of Wilson coefficients and their combinations in the Standard Model Effective Field Theory (SMEFT).
We study two approaches that aim at obtaining the full set of bounds for a given set of SM fields: 1) the traditional elastic positivity approach, which exploits the elastic scattering amplitudes of states with arbitrarily superposed helicities as well as other quantum numbers, and 2) the newly proposed extremal positivity approach, which constructs the allowed coefficient space directly by using the extremal representation of convex cones.
Considering the electroweak gauge-bosons as an example, we demonstrate how the best analytical and numerical positivity bounds can be obtained. While the new extremal approach is more constraining by construction, we also find that it is analytically easier to use, numerically much faster than the elastic approach, and much more applicable when more SM particle states and operators are taken into account.