The 3rd International Joint Workshop on the Standard Model and Beyond and the 11th KIAS Workshop on Particle Physics and Cosmology

The Suites Hotel, Jeju Island, Korea

The Suites Hotel, Jeju Island, Korea

67 Jungmungwangwang-ro 72beon-gil, 특별자치도, Seogwipo-si, Jeju-do
Eung Jin Chun (Korea Institute for Advanced Study), Tomasz Dutka (Korea Institute for Advanced Study), Jongkuk Kim (KIAS), Suro Kim, Pyungwon Ko (KIAS)

The "3rd International Joint Workshop on the Standard Model and Beyond" will be held jointly with the "11th KIAS Workshop on Particle Physics and Cosmology".


The aim of this meeting is to discuss recent developments in particle physics, cosmology and astroparticle physics in the context of testing the Standard Model (SM) and searches for new physics beyond the SM (BSM). This joint workshop will provide opportunities for collaboration between researchers from different institutes, and help young researchers better promote themselves in the community.


Participants are expected to arrive on Nov. 12 (Sun) and leave on Nov. 17 (Fri) and it will be held on Jeju Island, South Korea.


Invited Speakers

Joint Workshop:

  • Kento Asai (ICRR, U.Tokyo)
  • Hugues Beauchesne (NCTS)
  • Vu Hoa Binh (Institute of Physics, VAST)
  • Giorgio Busoni (ANU)
  • Jae Hyuk Chang (Fermilab)*
  • Gongjun Choi (University of Minnesota)*
  • Anthony Francis (NYCU)
  • Kohei Fujikura (U.Tokyo)
  • Juan Herrero-Garcia (Valencia U.)
  • Huai-Ke Guo (UCAS)*
  • Asuka Ito (QUP, KEK)
  • Ryusuke Jinno (Rescue, U.Tokyo)
  • Jeong Han Kim (CBNU)
  • Phan Hong Khiem (Duy Tan University)
  • Seung J. Lee (Korea University)
  • Qiuyue Liang (Kavli IPMU)
  • Gabriela Lima Lichtenstein (UNSW)
  • Yen-Hsun Lin (Academia Sinica)
  • Shohei Okawa (KEK)
  • Dipan Sengupta (Adelaide)
  • Martin Spinrath (NTHU)
  • Yong Tang (UCAS)
  • Yue-Lin Sming Tsai (Purple mountain observ.)
  • Po-Yan Tseng (NTHU)
  • Ning-Qiang Song (ITP-CAS)
  • German Valencia (Monash)

KIAS Workshop:

  • Kingman Cheung (NTHU)
  • Eung Jin Chun (KIAS)
  • Tomasz Dutka (KIAS)
  • Minxi He (IBS)
  • Dong Woo Kang (JBNU)
  • Kiyoharu Kawana (KIAS)
  • Joern Kersten (Yonsei University)*
  • Jinsu Kim (Tongji University)
  • Jongkuk Kim (KIAS)
  • Yechan Kim (KAIST)
  • Yuji Omura (Kindai University)
  • Alex Pomarol (UAB and IFAE)*
  • Jeonghyeon Song (Konkuk University)
  • Liliana Velasco-Sevilla (Sogang University)
  • Xing-Yu Yang (KIAS)
  • Chaehyun Yu (GNU)
  • Tzu Chiang Yuan (Academia Sinica)

* Indicates an online talk.

Important notices:

Deadline - Registration/Abstract submission: Oct. 20, 23:59, 2023 (KST).

- A number of rooms at the workshop hotel have been booked in preparation for the joint workshop.

- Invited speakers will have their accommodation (including breakfast) covered by the workshop. Others who also wish to stay at the same hotel can find details of the costs on the registration page.

- Organised lunches and dinners will be provided gratis to invited speakers. Otherwise, a registration fee for domestic and foreign participants will be charged to those who wish to attend alongside the invited speakers, details are provided on the registration page. If you plan to explore the local restaurants yourself, you do not need to pay the registration fee.

- For those in need of financial support: please indicate this on the registration form. There are some limited funds for speakers with insufficient budgets.

  • Alex Pomarol
  • Anthony Francis
  • Asuka Ito
  • Bingrong Yu
  • Chaehyun Yu
  • Dibyendu Nanda
  • Dipan Sengupta
  • Dong Woo Kang
  • Eung Jin Chun
  • Gabriela Lima Lichtenstein
  • German Valencia
  • Giorgio Busoni
  • Gongjun Choi
  • Hoa Binh Vu
  • Huaike Guo
  • Hugues Beauchesne
  • Jae Hyeok Chang
  • Jaehoon Jeong
  • Jaeok Yi
  • Jan Tristram Acuña
  • Jeong Han Kim
  • Jeonghyeon Song
  • Jiheon Lee
  • Jinsu Kim
  • Joern Kersten
  • Jongkuk Kim
  • Juan Herrero Garcia
  • Kazuki Enomoto
  • Kento Asai
  • Khiem Hong Phan
  • Kingman CHEUNG
  • Kiyoharu Kawana
  • Kohei Fujikura
  • Liliana Velasco-Sevilla
  • Martin Spinrath
  • Minxi He
  • Ningqiang Song
  • Po-Yen Tseng
  • Pyungwon Ko
  • Qiuyue Liang
  • Raymundo Ramos
  • Ryusuke Jinno
  • Seung J. Lee
  • Shohei Okawa
  • Suro Kim
  • TaeHun Kim
  • Thomas Flacke
  • Tian-Peng Tang
  • Tomasz Dutka
  • Tzu Chiang Yuan
  • Xinchen Duan
  • Xing-Yu Yang
  • Yechan Kim
  • Yen-Hsun Lin
  • Yong Tang
  • Yu-Hui Zheng
  • Yue-Lin Sming Tsai
  • Yuji Omura
    • Arrival
    • Registration
    • Reception
    • Morning Session
      Conveners: Pyungwon Ko (KIAS), Suro Kim
      • 1
        New physics in $B\to K^{(*)}\nu\bar\nu$

        We discuss the modes $B\to K^{(*)}\nu\bar\nu$ in the context of non-standard neutrino interactions and in the presence of new light (dark matter) particle pairs and consider the implications for additional $B$ decay modes. In particular, we consider the possibility of accommodating the new Belle II measurement.

        Speaker: German Valencia (Monash University)
      • 2
        Lepton-flavour-violating constraints from triality

        Triality models are motivated by flavour structure theories. They produce charged lepton flavour violation channels mediated by a doubly charged scalar. However, the triality charges forbid decays such as muon to electron conversions, avoiding stringent experimental bounds. We have calculated predictions of charged lepton violation in this scenario and show the complementarity between Belle II and muTristan searches.

        Speaker: Gabriela Lima Lichtenstein (University of New South Wales)
      • 3
        An EFT approach to lepton and baryon number violation

        In this presentation, I will discuss lepton and baryon number violation using an Effective Field Theory (EFT) approach. In particular, in the first part of the talk, I will analyse the generation of tree-level Majorana neutrino masses by the introduction of new scalar multiplets at the electroweak scale, which acquire vacuum expectation values (VEVs). We will elucidate the underlying UV completions for these effective operators, specifically the new seesaw models, and investigate their impact on neutrino masses, including contributions at the loop level. We will discuss the phenomenology of these scenarios, including constraints from Electroweak Precision Tests, Lepton Flavor Violation, and colliders. In the second part of the talk, I will explore nucleon decays using SMEFT operators up to dimension 9. We will present estimates for the rates of various nucleon decay channels and use these to extract model-independent lower limits on the energy scale associated with these processes. Additionally, we will investigate potential correlations among processes.

        Speaker: Juan Herrero Garcia (IFIC (University of Valencia - CSIC))
      • 10:30 AM
      • 4
        Zooming in on exotic multi-quark hadrons in QCD

        Fifty years after the discovery of QCD experimental and theoretical efforts continue to uncover structures in its spectrum - sometimes unexpectedly. In the heavy sector alone, for example, among the about 62 (LHCb'22) new hadron states observed, many are 4- or 5-quark states. These states are phenomenologically difficult to explain and conclusions are often contradictory depending on how QCD interactions are modelled. In this talk I will present current efforts to resolve parts of this impasse by performing QCD calculations without approximation using advanced lattice techniques. Focussing on doubly heavy tetraquarks, recent lattice calculations will be reviewed and paths towards understanding the substructure of these states sketched out. To illustrate I will give details on the possibility of understanding deeply bound doubly heavy tetraquarks in terms of diquark effective degrees of freedom and how the properties of these diquarks can be determined on the lattice.

        Speaker: Anthony Francis (National Yang Ming Chiao Tung University)
      • 5
        Renormalization group effects in QCD axion phenomenology

        We study the impact of renormalization group effects on QCD axion phenomenology. Focusing on the DFSZ model, we argue that the relevance of running effects for the axion couplings crucially depends on the scale where the heavier Higgs doublet, charged under the Peccei-Quinn symmetry, is integrated out. We study the impact of these effects on astrophysical and cosmological bounds as well as on the sensitivity of helioscopes experiments such as IAXO and XENONnT, showing that they can be sizable even in the most conservative case in which the two Higgs doublets remain as light as the TeV scale. We provide simple analytical expressions that accurately fit the numerical solutions of the renormalization group equations as a function of the mass scale of the heavy scalars.

        Speaker: Shohei Okawa (KEK)
    • 12:00 PM
    • Afternoon Session
      Conveners: Dibyendu Nanda (Indian Association for the Cultivation of Science), Jaehoon Jeong (KIAS)
      • 6

        We propose a leptogenesis scenario where the CP asymmetry is provided by the kinetic motion of the majoron in the decay and inverse decay of a right-handed neutrino which violates the lepton number by one unit. We find that successful leptogenesis can be achieved for sub-keV majoron which can be a viable dark matter candidate as well. If one considers a very strong wash-out regime requiring a huge kinetic misalignment, the right-handed neutrino mass can go down to the sub-GeV region which is sensitive to various HNL searches.

        Speaker: Eung Jin Chun (Korea Institute for Advanced Study)
      • 7
        Bubble-assisted Leptogenesis

        Without tuning of parameters, the typical mass scale of the lightest right-handed neutrino (RHN), in the thermal leptogenesis paradigm, is about 10^{11} GeV. As opposed to the mild departure from equilibrium offered by the slow expansion, a first-order phase transition (FOPT) offers a drastic scenario of out-of-equilibrium dynamics. In this work we explore the possibility of embedding thermal leptogenesis within a FOPT such that RHNs remain massless until the FOPT arises. Their sudden and violent mass gain allows the neutrinos to become thermally decoupled, and the lepton asymmetry generated from their decay can be free from the strong wash-out processes that conventional leptogenesis scenarios suffer from, although new and important washout channels are now predicted. This allows for a decrease in the RHN's mass scale, which we quantify, as well complementary gravitional wave signals.

        Speaker: Tomasz Dutka (Korea Institute for Advanced Study)
      • 8
        Non-thermal WIMPy baryogenesis from early matter-dominated epoch

        From satellite-based measurements, the Standard Model (SM) can explain only 5 percent of the energy density of the present Universe, and the baryon density at present infers the existence of baryon asymmetry of the Universe. About 26 percent of energy density consists of Dark Matter (DM), which plays a crucial role in large scale structure formations. In new theoretical models beyond the SM, there are many long-lived massive particles that can dominate the energy density of the Universe, and eventually decay. And, the matter-antimatter asymmetry should be produced after Inflation since the initial abundance of baryon asymmetry is diluted during Inflation. If we consider the early matter-dominated epoch, dark matter can be non-thermally produced during a reheating period, and subsequently annihilate again to lighter SM particles even after the thermal freeze-out. We will discuss the possibility that re-annihilation of dark matter provides the correct baryon asymmetry and the observed relic abundance of DM. In my presentation, I will talk about both DM and baryon asymmetry production with low reheating temperature triggered by the decay of a long-lived massive particle or by evaporation of primordial black holes.

        Speaker: Jongkuk Kim (KIAS)
      • 3:30 PM
      • 9
        Dirac-Majorana neutrino type oscillation induced by a wave dark matter

        The Dirac or Majorana nature of the neutrinos is still unrevealed. Such neutrino type is determined by the relative size of the Dirac and Majorana mass terms. These mass terms may oscillate if they couple to the wave dark matter. We show the oscillation amplitude can be large enough to change the neutrino type between Dirac and Majorana periodically while satisfying the constraints from dark matter physics. The neutrino type oscillation provides the modulation of the lepton number violation processes like neutrinoless double beta decay. The scale of the oscillation amplitude evolves as the energy density of dark matter decreases over cosmic time. It implies that there is an interesting connection between the leptogenesis in the early universe and the neutrino type oscillation in the present time. This talk is based on the recent paper (arXiv:2305.16900) with YeolLin ChoeJo and Hye-Sung Lee.

        Speaker: Yechan Kim (KAIST)
      • 10
        Sources for pulsar timing array observations
        Speaker: Xing-Yu Yang (Korea Institute for Advanced Study)
      • 4:50 PM
      • 11
        Gravitational wave search through electromagnetic telescopes

        We study the graviton-photon conversion in the magnetic fields of the Earth, pulsars, our galaxy, and intergalactic regions. Requiring that the photon flux converted from gravitons does not exceed the observed photon flux with telescopes, we derive upper limits on the stochastic gravitational waves in frequency ranges from 10^7Hz to 10^35Hz. The detection of gravitational waves using telescopes may open up a new avenue for high frequency gravitational wave observations.

        Speaker: Asuka Ito (QUP/KEK)
      • 12
        Geometric view for the pNGB potential

        We investigate the pseudo-Nambu-Goldstone bosons (pNGBs) potential in the geometrical point of view. In this talk I will discuss how to essentially organise or structurally understand the pNGB potential without recourse to the UV symmetries.

        Speaker: Dong Woo Kang (Jeonbuk National University)
    • 6:00 PM
    • Evening Session
      Conveners: Kiyoharu Kawana (KIAS), TaeHun Kim (KIAS)
      • 13
        Potential of the HL-LHC to probe light fermiophobic Higgs boson signals via diphoton jets

        We study the phenomenological signatures associated with a light fermiophobic Higgs boson within the type-I two-Higgs-doublet model at the HL-LHC. Our exhaustive parameter scan revealed a captivating mass range between 1 GeV and 10 GeV. This range retains a substantial number of viable parameter points, primarily due to the current experimental difficulties in probing soft decay products of the light fermiophoibic Higgs, two photons. A major obstacle arises as two photons from the $\hf$ decay tend to merge into one jet because of their proximity. This leads to dominating QCD backgrounds. To address this, we utilize EFlow objects within the Delphes framework, identifying a jet containing two photons, termed a diphoton jet. Through our full detector-level simulations across 18 benchmark points, the majority presented signal significances beyond 5 at an integrated luminosity of 3/ab. In challenging scenarios with a heavier charged Higgs boson, our incorporation of machine learning techniques demonstrated a significant enhancement.

        Speaker: Jeonghyeon Song (Konkuk University)
      • 14
        Deep Learning Higgs Images
        Speaker: Jeong Han Kim (Chungbuk National University)
      • 15
        Uncovering doubly charged scalars with dominant three-body decays using machine learning

        We propose a deep learning-based search strategy for pair production of doubly charged scalars undergoing three-body decays to Wtb pairs in the same-sign lepton plus multi-jet final state. This process is motivated by composite Higgs models with an underlying fermionic UV theory. We demonstrate that for such busy final states, jet image classification with convolutional neural networks outperforms standard fully connected networks acting on reconstructed kinematic variables. We derive the expected discovery reach and exclusion limit at the high-luminosity LHC.

        Speaker: Thomas Flacke (KIAS)
      • 16
        Predicting the importance of complicated regions in Monte Carlo sampling

        In this talk we discuss a proposal where a neural network is trained to classify regions in multidimensional parameter space according to a function that determines their importance. These regions in general can have complicated shapes and disconnected subregions. Accurate classification of regions of importance with a neural network can improve event generation and Monte Carlo integration, specially for costly time consuming calculations.

        Speaker: Raymundo Ramos (KIAS)
      • 17
        A cosmological sandwiched window for seesaw with primordial majoron abundance

        A singlet majoron can arise from the seesaw framework as a pseudo-Goldstone boson when the heavy Majorana neutrinos acquire masses via the spontaneous breaking of global U(1)_L symmetry. The resulting cosmological impacts are usually derived from the effective majoron-neutrino interaction, and the majoron abundance is accumulated through the freeze-in neutrino coalescence. However, a primordial majoron abundance can be predicted in a minimal setup and lead to distinctive cosmological effects. In this work, we consider such a primordial majoron abundance from relativistic freeze-out and calculate the modification to the effective neutrino number Neff. We demonstrate that the measurements of Neff will constrain the parameter space from a primordial majoron abundance in the opposite direction to that from neutrino coalescence. When the contributions from both the primordial abundance and the freeze-in production coexist, the U(1)_L-breaking scale (seesaw scale) f will be pushed into a "sandwiched window".
        Remarkably, for majoron masses below 1 MeV and above the eV scale, the future CMB-S4 experiment will completely close such a low-scale seesaw window for f ∈ [1,10^5] GeV. We highlight that any new light particle with a primordial abundance that couples to Standard Model particles may lead to a similar sandwiched window, and such a general phenomenon deserves careful investigation.

        Speaker: Bingrong Yu (Cornell University)
    • Morning Session
      Conveners: Thomas Flacke (KIAS), Yu-Hui Zheng (Korea Institute for Advanced Study)
      • 18
        New Physics Search at Long-lived Particle Search Experiments

        Recently, experiments for long-lived particle search are recently focused on from both theoretical and experimental points of views. This kind of experiment has advantages of low background and high luminosity and can explore light particles beyond the Standard Model (BSM) feebly coupled to the SM particles. In my talk, I explain the recent works about the explorations of the BSM physics at long-lived particle search experiments.

        Speaker: Kento Asai (ICRR, the University of Tokyo)
      • 19
        Observability of the Higgs boson decay to a photon and a dark photon

        Many collider searches have attempted to detect the Higgs boson decaying to a photon and an invisible massless dark photon. For the branching ratio to this channel to be realistically observable at the LHC, there must exist new mediators that interact with both the standard model and the dark photon. In this talk, we present experimental and theoretical constraints on an extensive set of mediator models. We show that these constraints limit the Higgs branching ratio to a photon and a dark photon to be far smaller than the current sensitivity of collider searches.

        Speaker: Hugues Beauchesne (NCTS)
      • 20
        One-loop expressions for h→ll¯γ in Higgs extensions of the Standard Model

        A systematic study of one-loop contributions to the decay channels h→ll¯γ with l=νe,μ,τ,e,μ, performed in Higgs extended versions of the Standard Model, is presented in the 't Hooft-Veltman gauge. Analytic formulas for one-loop form factors are expressed in terms of the logarithm and di-logarithmic functions. As a result, these form factors can be reduced to those relating to the loop-induced decay processes h→γγ,Zγ, confirming not only previous results using different approaches but also close relations between the three kinds of the loop-induced Higgs decay rates. For phenomenological study, we focus on the two observables, namely the enhancement factors defined as ratios of the decay rates calculated between the Higgs extended versions and the standard model, and the forward-backward asymmetries of fermions, which can be used to search for Higgs extensions of the SM. We show that direct effects of mixing between neutral Higgs bosons and indirect contributions of charged Higg boson exchanges can be probed at future colliders.

        Speaker: Khiem Hong Phan (Institute of Fundamental and Applied Sciences, Duy Tan University, Ho Chi Minh City 700000, Vietnam; Faculty of Natural Sciences, Duy Tan University, Da Nang City 550000, Vietnam)
      • 10:30 AM
      • 21
        New scalar fields in the 3-3-1 model with axion-like particle

        The scalar sector of the 3-3-1 model with axion like particle is studied in detail. In the model under consideration, there are two kinds of scalar fields: the bilepton scalars carrying lepton number two and the ordinary ones without lepton number. We show that there is no mixing among these two kinds of scalar fields. We analyze in detail the CP-odd scalar sector of the model to find the physical fields of the axion like particle and a pseudoscalar with mass in the range 100 GeV to 1 TeV. The results are different from others which have been published before. The CP-even scalar sector of the model is analyzed as well. The results of our analysis of the scalar sector allow the existence of a non SM scalar boson with mass around 96 GeV or another one with mass around 150 GeV. Furthermore, we analyze the implications of the model in several flavor changing neutral decays of the top quark as well as in rare top quark decays. Besides that, the leptonic decays of the SM like Higgs boson as well as the meson oscillations are analyzed as well as. Our numerical analysis show that the model under consideration is consistent with the experimental constraints imposed by these processes.

        Speaker: Hoa Binh Vu (Institute of Physics, Vietnam Academy of Sciences and Technology)
      • 22
        Recent Progress in Minimal G2HDM Phenomenology
        Speaker: Tzu Chiang Yuan (Institute of Physics, Academia Sinica)
    • 12:00 PM
    • Free discussion
    • 6:00 PM
    • Evening Session
      Conveners: Jaehoon Jeong (KIAS), Dibyendu Nanda (Indian Association for the Cultivation of Science)
      • 23
        (Zoom) Bootstrapping BSM theories
        Speaker: Alex Pomarol (UAB and IFAE)
      • 24
        Fine tuning as quantum phase transition point

        We discuss a possibility to solve fine-tuning problems based on micro-canonical formulation of quantum field theory.

        Speaker: Kiyoharu Kawana (KIAS)
      • 25
        Scattering Amplitudes and Goldstone Boson Equivalence Theorem in Flat and Warped Extra Dimensions

        Scattering Amplitudes are crucial to understanding the range of validity of effective field theories. In this talk I will talk about the unitarity and validity of extra dimensional gravity and demonstrate that the Goldstone Boson Equivalence Theorem ensures that high energy scattering of massive Kaluza-Klein states are unitary through a series of Ward Identities. Furthermore I will show that the Goldstone Boson Equivalence theorem can be used to demonstrate gauge and gravity double copy in extra dimensions.

        Speaker: Dipan Sengupta (University of Adelaide)
      • 26
        2HDM with Gauged Higgs Fields
        Speaker: Chaehyun Yu (GNU)
    • Morning Session
      Conveners: Jongkuk Kim (KIAS), Tomasz Dutka (Korea Institute for Advanced Study)
      • 27
        Forbidden Conformal Dark Matter at a GeV

        In this talk, I will present a new model of DM where the DM is a composite of a spontaneously broken conformal field theory. The DM is a thermal relic with its abundance determined by the freeze-out of annihilations to dilatons, the Goldstone boson of broken conformal symmetry. If the dilaton is heavier than the DM this is an example of forbidden DM. I will present a fully realistic model that describes this DM candidate and its interactions with ordinary particles with masses in the 0.1-10 GeV range. The conformal phase transition is supercooled and strongly first-order. It can source large stochastic gravitational wave signals consistent with those recently observed at pulsar timing arrays like NANOGrav. The majority of the viable parameter space will be probed by future detectors designed to search for long-lived particles, including most of the region favored by the NANOGrav signal. The rest of the parameter space can be probed at future direct detection experiments.

        Speaker: Seung J. Lee (Korea University)
      • 28
        Detecting Non-Gravitational interaction of Dark Matter in Cosmology: A Case Study of Mirror Dark Matter.

        In this talk, I will first try to discuss why the particle nature of dark matter is one of the most important topics of the modern physics from the historical development and frontier research of dark matter, and whether the evidence for dark matter reveals only gravitational interaction. Then, I will take one of the simplest dark matter models - mirror dark matter (the dark sector behaves like a mirror sector of the visible world) - as an example. We will first demonstrate that non-gravitational forces can not only solve cosmological problems, such as the Hubble and S8 tensions, but also use the weak gravitational lensing data from the future Chinese Space Station Telescope (CSST) to accurately determine the possible relic of mirror dark matter. Finally, we combine (i) gravitational lensing constraints, (ii) stochastic gravitational wave detection from pulsar timing arrays, and (iii) precise measurements of CMB+BAO to predict the possible degrees of freedom of relativistic particles.

        Speaker: Yue-Lin Sming Tsai (Purple Mountain Observatory)
      • 29
        Detecting afterglow signatures from light dark matter boosted by supernova neutrinos

        Supernova neutrino boosted dark matter (SNν BDM) and its afterglow effect stand as promising signatures for exploring beyond Standard Model (bSM) physics. The unique time-evolution feature of SNν BDM offers a direct avenue for inferring DM mass, concurrently leading to substantial background reduction with increasing sensitivity. In this talk, I will expound upon the SNν BDM framework applicable to next supernovae occurring anywhere in our galaxy, emphasizing its distinctive signatures that facilitate DM mass extraction. Additionally, I will present anticipated sensitivities on DM-ν and DM-e cross sections, derived from experiments including Super-Kamiokande, Hyper-Kamiokande, and DUNE, and compare these projected results with existing constraints

        Speaker: Yen-Hsun Lin (Academia Sinica)
      • 10:30 AM
      • 30
        Light mass window of lepton portal dark matter

        We explore a novel possibility that dark matter has a light mass below 1 GeV in a lepton portal dark matter model. There are Yukawa couplings involving dark matter, left-handed leptons and an extra scalar doublet in the model. In the light mass region, dark matter is thermally produced via its annihilation into neutrinos. In order to obtain the correct relic abundance and avoid collider bounds, a neutral scalar is required to be light while charged scalars need to be heavier than the electroweak scale. Such a mass spectrum is realized by adjusting quartic couplings in the scalar potential or introducing an extra singlet scalar. We also discuss the signals of our model at the LHC.

        Speaker: Yuji Omura (Kindai University)
      • 31
        Emergent particles of de Sitter universe: thermal interpretation of the stochastic formalism and beyond

        A thermal interpretation of the stochastic formalism of a slow-rolling scalar field in a de Sitter (dS) universe is given. By introducing a notion of emergent particles and a dual description of scalar fields, we show that the stochastic evolution of the infrared part of the field is equivalent to the Brownian motion in an abstract space filled with a heat bath of massless particles. The 1st slow-roll condition and the Hubble expansion are also reinterpreted in the abstract space as the speed of light and a transfer of conserved energy, respectively. Inspired by this, we sketch the quantum emergent particles, which may realize the Hubble expansion by an exponential particle production. This gives another meaning of dS entropy as entropy per Hubble volume in the global dS universe.

        Speaker: Dr TaeHun Kim (KIAS)
      • 32
        Characterizing the hypercharge anapole dark matter particle

        We consider the case that dark matter (DM) is solely composed of se lf-conjugate (Majorana) particle interacting with ordinary standard model (SM) matter exclusively through so-called U(1) hypercharge anapole terms. Based on the general three-point vertices of a virtual photon $\gamma$ and a massive gauge boson $Z$ and two identical on-shell particles of any spin $J$ and mass $m$, we evaluate the relic abundance and the direct detection cross sections. Combining the constraints from these experiments and those from the high-energy Large Hadron Collider (LHC) experiments, we perform a systematic investigation of whether the limits on the mass and coupling strengthes depend on the spin of the anapole DM.

        Speaker: Jaehoon Jeong (KIAS)
    • 12:10 PM
    • Afternoon Session
      Conveners: Tomasz Dutka (Korea Institute for Advanced Study), Thomas Flacke (KIAS)
      • 33
        Probing Ultralight Dark Matter with Space-based Gravitational-Wave Interferometers

        Ultralight bosonic fields (ULBFs) are predicted by various theories beyond the standard model of particle physics and are viable candidates of cold dark matter. There have been increasing interests to search for the ULBFs in physical and astronomical experiments. In this paper, we investigate the sensitivity of several planned space-based gravitational-wave interferometers to ultralight scalar and vector fields. Using time-delay interferometry (TDI) to suppress the overwhelming laser frequency noise, we derive the averaged transfer functions of different TDI combinations to scalar and vector fields, and estimate the impacts of bosonic field's velocities. We obtain the sensitivity curves for LISA, Taiji and TianQin, and explore their projected constraints on the couplings between ULBFs and standard model particles, illustrating with the ULBFs as dark matter.

        Speaker: Yong Tang (University of Chinese Academy of Sciences)
      • 34
        Dark Matter Capture, Multiple Scattering and Thermalsation in Compact Stars

        Dark Matter candidates with cross sections as tiny as can be captured efficiently in compact stars, like Neutron Stars and White Dwarfs. The collisions to capture Dark Matter would heat the star, raising its equilibrium temperature, around 2000K for a NS. Thus, observation of old and cold NS that should have reached equilibrium can be used to set constraints on the capture cross section. In this talk, I present the formalism to calculate capture rates in NS and WD in the optically thin and optically thick regimes, and the limits on the DM-nucleuon cross section that one could infer from non-observation. We use a similar formalism to calculate the thermalisation time in both NS and WD, and we use this to discuss for which operators DM can be expected to be in thermal equilubrium and/or in Capture-Annihilation equilibrium.

        Speaker: Giorgio Busoni (The Australian National University)
      • 35
        Earth and Celestial Bodies as Dark Matter Laboratories

        Celestial bodies are well motivated laboratories for dark matter searches. I will give two such examples. In the first scenario, dark matter gets captured in the Earth by scattering with Earth nuclei. The accumulated dark matter annihilates and yields excessive heat. In the other scenario, dark photons resonantly convert to photons in the atmosphere of neutron stars or white dwarfs, producing signals in the radio frequencies that are detectable on the Earth with radio telescopes.

        Speaker: Ningqiang Song (Institute of Theoretical Physics, Chinese Academy of Sciences)
      • 3:30 PM
      • 36
        Gauged quintessence : dark energy with gauge symmetry

        We introduce the gauged quintessence model, in which the dark energy field (quintessence) has a U(1) gauge symmetry. We identify the real part of the complex scalar as the dark energy field (quintessence), while the imaginary part is the longitudinal component of a new gauge boson. It brings interesting characters to dark energy physics. The U(1) gauge boson can affect the quintessence dynamics, and the solicited dark energy properties can constrain the gauge coupling constant. While the uncoupled quintessence model severely suffers from the Hubble tension, the gauged quintessence might alleviate the situation.

        Speaker: Jiheon Lee (Korea Advanced Institute of Science and Technology)
      • 37
        Misalignment mechanism for a mass-varying vector boson

        A coherent field over the entire universe is an attractive picture in studying the dark sector of the universe. The misalignment mechanism, which relies on inflation to achieve homogeneousness of the field, is a popular mechanism for producing such a coherent dark matter. Nevertheless, unlike a scalar field case, a vector boson field suffers because its energy density is exponentially suppressed by the scale factor during the cosmic expansion. We show that if the vector field gets a mass from a scalar field, whose value increases by orders of magnitude, the suppression can be compensated, and the misalignment can produce the coherent vector boson that has a sizable amount of energy density in the present universe. Quintessence can be such a scalar field.

        Speaker: Jaeok Yi (KAIST)
      • 38
        Light Thermal Self-Interacting Dark Matter in the Shadow of Non-Standard Cosmology

        In this paper, we construct a viable model for a GeV scale self-interacting dark matter (DM), where the DM was thermally produced in the early universe. In this model, a new vector-like fermion with a dark charge under the $U_{D}$ gauge symmetry serves as a secluded WIMP DM and it can dominantly annihilate into the light dark gauge boson and singlet scalar through the dark gauge interaction. Also, the self-interaction of DM is induced by the light dark gauge boson via the same gauge interaction. In addition to these particles, we further introduce two Weyl fermions and a doublet scalar, by which the dark gauge boson produced from $s$-wave DM annihilations can mostly decay into active neutrinos after the dark symmetry breaking such that the CMB bound on the DM with low masses can be eluded. In order to have a common parameter region to explain the observed relic abundance and self-interaction of DM, we also study this model in a non-standard cosmological evolution, where the cosmic expansion driven by a new field species is faster than the standard radiation-dominated universe during the frozen time of DM. Reversely, one can also use the self-interacting nature of light thermal DM to examine the non-standard cosmological history of the universe.

        Speaker: Dibyendu Nanda (KIAS)
      • 4:50 PM
      • 39
        Dark Z boson and the W boson mass anomaly

        The dark Z boson is a new vector particle induced by an additional Abelian gauge symmetry. It interacts with the SM fermions via kinetic and mass mixings and provides a new source of parity violation. It is known that such a parity-violating effect can be tested by future precious measurements of the weak mixing angle at low energies. In this talk, we discuss the effect of the dark Z boson on the W boson mass measurement. Mixings between dark Z and the electroweak gauge bosons induce deviations in the SM gauge couplings, and it gives a possibility of explaining the W boson mass anomaly reported by the CDF collaboration. We will show that the dark Z model can explain the W boson mass anomaly while satisfying other experimental constraints within 2σ; on the other hand, the simple dark photon model cannot. We also discuss how to verify such a dark Z boson in future experiments.

        Speaker: Kazuki Enomoto (KAIST)
      • 40
        Self-interacting dark matter and the GRB221009A event

        In this work, we explore the intriguing possibility of connecting self-interacting dark matter (SIDM) with the recently observed exceptionally bright and long-duration Gamma Ray Burst (GRB221009A). The proposed minimal scenario involves a light scalar mediator, simultaneously enabling dark matter (DM) self-interaction and explaining the observed very high energy (VHE) photons from GRB221009A reported by LHAASO’s data. The scalar’s mixing with the standard model (SM) Higgs boson allows for its production at the GRB site, which will then propagate escaping attenuation by the extra-galactic background light (EBL). These scalars, if highly boosted, have the potential to explain LHAASO’s data. Moreover, the same mixing also facilitates DM-nucleon or DM-electron scatterings at terrestrial detectors, linking SIDM phenomenology to the GRB221009A events. This manuscript presents the parameter space meeting all constraints and offers an exciting opportunity to explore SIDM in future direct search experiments using insights from the GRB observation.

      • 41
        Light thermal Dark Matter Beyond p-Wave Annihilation

        We investigate a minimal renormalizable model that incorporates a light fermionic weakly interacting massive particle (WIMP) dark matter (DM) and a mediator for interactions with standard model particles. Our comprehensive likelihood analysis considers constraints from direct detection experiments, collider searches, cosmological observations, and astrophysical observations. In particular, we account for constraints derived from cosmic microwave background (CMB) observations, taking into consideration dark matter annihilation processes beyond p-wave. Remarkably, despite these constraints, we found a significant parameter space where dark matter can persist. Furthermore, we also found that future indirect detection experiments can offer promising prospects for probing the resonant annihilation regions of dark matter.

        Speaker: Tian-Peng Tang (Purple Mountain Observatory, Chinese Academy of Sciences)
    • 6:00 PM
    • Evening Session
      Conveners: Xing-Yu Yang, Raymundo Ramos (KIAS)
      • 42
        The signatures of sub-solar-mass primordial black holes

        511 keV gamma-ray excess from the Galactic center is a long lasting anomaly without satisfying astrophysical explanation. Hawking evaporation of hypothetical primordial black hole (PBH) with mass ${\color{blue}1.0\times 10^{-17} \lesssim M_{\rm PBH}/M_\odot \lesssim 8.0\times 10^{-17}}$ and fractional abundance ${\color{blue}10^{-3} \lesssim f_{\rm PBH} \lesssim 1.0}$, gives rise substantial non-relativistic electrons/positrons annihilating into diphoton, well reproduces the 511 keV line. However, it is obscure of the mechanism behind to form PBH with meteoritical mass in the early Universe. In this work, we investigated the production mechanism of PBHs through a cosmological first-order phase transition induced by quartic effective thermal potential via a scalar field in dark sector. We found the phase transition with vacuum energy, $\mathcal{O}(1)\lesssim B^{1/4}/{\rm MeV} \lesssim \mathcal{O}(100)$, produces the desired monochromatic PBH mass and abundance fraction. Correlated signatures of gravitational wave and extragalactic gamma-ray, respectively coming from phase transition and black hole evaporation, are within $\mu$Ares and AMEGO/e-ASTROGAM/COSI/XGIS-THESUS projected sensitivities. Finally, we include the PBH mass function from FOPT and found it can not improve the explanation to 511 keV excess.

        Speaker: Po-Yen Tseng (National Tsing Hua University)
      • 43
        Dark Matter Searches in GW Detectors

        In my talk I will discuss our recent work in studying the prospects to look for Dark Matter in Gravitational Wave Detectors, in particular in KAGRA. While the prospects for conventional particle Dark Matter are rather bleak, it might be possible to detect heavy (kg-scale) Dark Matter. If time allows, I will also briefly comment on other peoples work looking for very light Dark Matter in KAGRA.

        Speaker: Martin Spinrath (NTHU/NCTS)
      • 44
        NANOGrav Signal and PBH from the Modified Higgs Inflation

        This study investigates the classical Higgs inflation model with a modified Higgs potential fea- turing a dip. We examine the implications of this modification on the generation of curvature perturbations, stochastic gravitational wave production, and the potential formation of primordial black holes (PBHs). Unlike the classical model, the modified potential allows for enhanced power spectra and the existence of PBHs within a wide mass range 1.5 × 10^20 g – 9.72 × 10^32 g. We identify parameter space regions that align with inflationary constraints and have the potential to contribute significantly to the observed dark matter content. Additionally, the study explores the consistency of the obtained parameter space with cosmological constraints and discusses the implications for explaining the observed excess in gravitational wave signals, particularly in the NANOGrav experiment. Overall, this investigation highlights the relevance of the modified Higgs potential in the classical Higgs inflation model, shedding light on the formation of PBHs, the nature of dark matter, and the connection to gravitational wave observations.

        Speaker: Kingman CHEUNG (National Tsing Hua University / Konkuk University)
      • 45
        Probing primordial black holes from a first order phase transition through pulsar timing and gravitational wave signals

        We assessed the sensitivity of SKA-like pulsar timing measurements to probe signals of a first order phase transition (FOPT) scenario in the dark sector, which gives rise to primordial black holes (PBHs) and stochastic gravitational waves (GWs). We considered the mechanism where the PBHs are formed from the collapse of Fermi balls created from dark matter filtered out of true vacuum bubbles. In probing these PBHs, the relevant signal is the Doppler phase shift in the pulsar timing signal. Under certain conditions, we found that critical temperatures of interest lie in the 0.1-10 keV range. For the same set of parameters characterizing the FOPT, the resulting stochastic GW spectrum falls within the sensitivity reach of a simultaneous SKA-like search for stochastic GWs, and can be used as a complementary probe. Finally, by considering an explicit form for the dark scalar potential, we performed a parameter scan to identify the class of generic quartic potentials that could lead to viable FOPT scenarios that can be probed by SKA. The results of our scan may provide a useful reference to readily obtain phenomenological constraints on specific models that give rise to FOPTs.

        Speaker: Jan Tristram Acuña (National Tsing Hua University)
    • Morning Session
      Conveners: TaeHun Kim (KIAS), Xing-Yu Yang
      • 46
        Gravitational waves from Gauss-Bonnet-corrected inflation

        I shall discuss gravitational wave signatures coming from a single-field inflation model in which the inflaton couples to the Gauss-Bonnet term. When the scalar potential term and the Gauss-Bonnet coupling term have different signs, a nontrivial fixed point arises, effectively inducing ultra slow-roll inflation. In this case, primordial black holes can form, together with enhanced scalar-induced gravitational waves. When the scalar potential term and the Gauss-Bonnet coupling term have same signs, on the other hand, there may exist a region where the Gauss-Bonnet term briefly dominates. In this case, the primordial inflationary gravitational waves can be enhanced. The detectability of the gravitational wave signals shall be discussed as well.

        Speaker: Jinsu Kim (Tongji University)
      • 47
        One-loop effect in Higgs inflation

        Higgs inflation is a well-motivated inflation model because of its compatibility with observations and minimality by utilizing the Standard Model Higgs with non-minimal coupling to gravity. However, this model becomes strongly-coupled during preheating, which jeopardizes the validity of predictions by this model. Many efforts have been paid to avoid this strong coupling issue by UV-extending the Higgs inflation. In this talk, I will discuss the one-loop correction to the Higgs inflation which generally induces a new scalar degree of freedom, the scalaron, that can play an important role in UV-extension of the original model, and the inflation dynamics in the presence of the scalaron. In particular, my discussion is based on the Higgs inflation in Einstein-Cartan gravity which is a general setup that includes two commonly discussed versions of Higgs inflation, i.e. the metric and the Palatini Higgs inflation.

        Speaker: Minxi He (IBS)
      • 48
        Gravitational Waves from Feebly Interacting Particles in a First Order Phase Transition

        First order phase transitions are well-motivated and extensively studied sources of gravitational waves (GWs) from the early Universe. The vacuum energy released during such transitions is assumed to be transferred primarily either to the expanding walls of bubbles of true vacuum, whose collisions source GWs, or to the surrounding plasma, producing sound waves and turbulence, which act as GW sources. In this Letter, we study an alternative possibility that has so far not been considered: the released energy gets transferred primarily to feebly interacting particles that do not admit a fluid description but simply free-stream individually. We develop the formalism to study the production of GWs from such configurations, and demonstrate that such GW signals have qualitatively distinct characteristics compared to conventional sources and are potentially observable with near-future GW detectors.

        Speaker: Ryusuke Jinno (RESCEU, The University of Tokyo)
      • 49
        Next Year's Workshop Announcement
        Speaker: Dipan Sengupta (University of Adelaide)
      • 10:35 AM
      • 50
        Interactions between several types of cosmic strings

        We study the interaction of several types of static straight cosmic strings, including local strings, global strings, and bosonic superconducting strings with and without magnetic currents. First, we evaluate the interaction energy of two widely separated cosmic strings using the point source formalism and show that the most dominant contribution to the interaction energy comes from the excitation of the lightest mediator particles in a underlying theory. The interaction energy at arbitrary separation distances is then analyzed numerically by the gradient flow method. It turns out that an additional scalar field introduced in the bosonic superconducting string becomes an additional source of attraction. For such a bosonic superconducting string, we find that a string with two winding numbers is energetically favorable compared to two strings with a single winding number in a certain parameter region. Our analysis reveals that a phase structure of bosonic superconducting strings is richer than that of local and global strings and that the formation of bound states at intersections of bosonic superconducting strings is favored.

        Speaker: Kohei Fujikura (The University of Tokyo)
      • 51
        Using Gravitational Waves to constraint the Reheating Temperature

        The advent of using Gravitational Waves (GW) as a powerful method to understand the evolution of our early universe has arrived. In this talk, I will present an example of how the reheating temperature can be constrained only from GW coming from the Standard Model of Particle Physics plasma of the early universe both in Standard Cosmology and in a particular Gauss-Bonnet Scenario. In addition, if information of a particular model for inflation is given, this can constrain further the reheating temperature.

        Speaker: Liliana Velasco-Sevilla (Sogang University)
    • 12:00 PM
    • Free discussion
    • 6:00 PM
    • Morning Session
      Conveners: Suro Kim, Tomasz Dutka (Korea Institute for Advanced Study)
      • 52
        (Zoom) Implication of High Quality QCD axion in Dual Description
        Speaker: Gongjun Choi (University of Minnesota)
      • 53
        (Zoom) Dark Solar Wind

        We study the solar emission of light dark sector particles that self-interact strongly enough to self-thermalize. The resulting outflow behaves like a fluid which accelerates under its own thermal pressure to highly relativistic bulk velocities in the solar system. Compared to the ordinary noninteracting scenario, the local outflow has at least ~10^3 higher number density and correspondingly at least ∼10^3 lower average energy per particle. We show how this generic phenomenon arises in a dark sector composed of millicharged particles strongly self-interacting via a dark photon. The millicharged plasma wind emerging in this model has novel yet predictive signatures that encourage new experimental directions. This phenomenon demonstrates how a small step away from the simplest models can lead to radically different outcomes and thus motivates a broader search for dark sector particles.

        Speaker: Jae Hyeok Chang (Fermilab and UIC)
      • 54
        (Zoom) Fermion Mass Hierarchy in a Multi-Higgs Model

        While the properties of the observed Higgs boson agree with the Standard Model predictions, the hierarchy of fermion masses lacks an explanation within the model. In this work, we propose a fresh approach to this problem, involving a different Higgs doublet responsible for each quark mass. We construct a model with a gauged, non-anomalous $U(1)$ family symmetry that fixes which fermion couples to which doublet with an $\mathcal{O}(1)$ Yukawa coupling. The hierarchy of masses is generated by the hierarchy of vacuum expectation values of the Higgs fields. The model generically predicts a light, weakly coupled pseudoscalar. We verify that the model satisfies constraints from flavour changing neutral currents, Higgs phenomenology and electroweak precision tests.

        Speaker: Joern Kersten (Yonsei University)
      • 10:30 AM
      • 55
        (Zoom) Some Recent Developments on BSM Probes with Gravitational Waves

        I will describe some recent developments on using gravitational waves in searches for BSM: from phase transitions in the early universe, to searches of topological defects at LIGO, and searches for dark matter with gravitational waves.

        Speaker: Huaike Guo (University of Chinese Academy of Sciences (ICTP-AP))
      • 56
        (Zoom) Probing Parity Violation in the Stochastic Gravitational Wave Background with Astrometry

        Astrometry holds the potential for testing fundamental physics through the effects of the Stochastic Gravitational Wave Background (SGWB) in the ∼1−100 nHz frequency band on precision measurements of stellar positions. Such measurements are complementary to tests made possible by the detection of the SGWB using Pulsar Timing Arrays. Here, the feasibility of using astrometry for the identification of parity-violating signals within the SGWB is investigated. This is achieved by defining and quantifying a non-vanishing EB correlation function within astrometric correlation functions, and investigating how one might estimate the detectability of such signals.

        Speaker: Qiuyue Liang (Kavli IPMU)
    • 12:00 PM
      Lunch and Departure