2024 CAU-PNU Beyond the Standard Model Workshop

Centennial 310-B502 (Chung-Ang University)

Centennial 310-B502

Chung-Ang University

Chung-Ang University, Seoul, Republic of Korea.
Hyun Min Lee (CAU - Chung-Ang University (KR))

The 2024 Chung-Ang University Beyond the Standard Model (CAU BSM) Workshop is the fourth international meeting on Physics Beyond the Standard Model (Higgs, Dark Matter, Neutrino, Axion, Flavor, Inflation, Gravitational Waves) in Chung-Ang University, Korea. The aim of the BSM Workshop is to discuss interesting current topics and initiate the collaboration between experts and participants working on BSM physics in the globe. The fourth workshop will be held as the joint efforts between CAU, Pusan National University and Yonsei University. Registered participants are supposed to attend the workshop only in person. We hope that the CAU workshop is to keep the community moving with lively discussion and participation.

The map for the lecture room, 310-B502, can be found in https://neweng.cau.ac.kr/cms/FR_CON/index.do?MENU_ID=950#;


The workshop program is now complete. 


Time table





Group photos


Invited speakers

Guillermo Ballesteros (Madrid, IFT)

Nicolas Bernal (New York Univ, Abu Dabhi)

Kiwoon Choi (IBS CTPU)

Ki-Young Choi (SKKU)

Daniel Figueroa (Valencia Univ)

Dumitru Ghilencea (Bucharest, IFIN-HH) - zoom

Bogeun Gwak (Dongguk Univ)

Young-Hwan Hyun (KASI)

Sang Hui Im (IBS CTPU)

Tae Hyun Jung (IBS CTPU)

Sin Kyu Kang (Seoultech)

Tae Jeong Kim (Hanyang Univ)

Pyungwon Ko (KIAS)

Emi Kou (IJCLab, Orsay)

Youngjoon Kwon (Yonsei Univ)

Hyunsu Lee (IBS CUP)

Sung Mook Lee (KAIST)

Matthew Mccullough (CERN) - zoom

Chang Seong Moon (KNU)

Jong-Chul Park (Chungnam National Univ)

Myeonghun Park (Seoultech)

Chia-Hsien Shen (NTU)

Chang Sub Shin (Chungnam National Univ)

Seodong Shin (Jeonbuk National Univ)

Minho Son (KAIST)

Fuminobu Takahashi (Tohoku Univ)

Masahide Yamaguchi (IBS CTPU-CGA)

Dong-han Yeom (PNU)

SungWoo Youn (IBS CAPP)

Seokhoon Yun (IBS CTPU)




The third series: 2023 CAU BSM Workshop

The second series: 2022 CAU BSM Workshop

The first series: 2021 CAU BSM Workshop

CAU Department of Physics: http://physics.cau.ac.kr

CAU THEP Group: https://sites.google.com/site/cautheplab

CAU HEP Center: https://hep.cau.ac.kr


  • Adriana Guerrero Menkara
  • Alexey Zhevlakov
  • Ankit Kumar Bhagat
  • Anubhav Mahapatra
  • Arpan Kar
  • Arpan Kar
  • Bin Zhu
  • Bogeun Gwak
  • Carlo Branchina
  • Chang Hyeon Lee
  • Chang Hyon Ha
  • Chang Sub SHIN
  • Chang-Seong Moon
  • Chia-Hsien Shen
  • Daniel G. Figueroa
  • Dhong Yeon Cheong
  • Dong Woo Kang
  • Dong-han Yeom
  • Dumitru Ghilencea
  • Emi Kou
  • Eun-Kyung Park
  • Eunji Jang
  • Fuminobu Takahashi
  • Guillermo Ballesteros
  • Gungwon Kang
  • Hyun Min Lee
  • Hyunsu Lee
  • Jaehoon Jeong
  • Jaeok Yi
  • Jeonghak Han
  • Jiheon Lee
  • Jiyoon Sun
  • Jong-Chul Park
  • Jongkuk Kim
  • Joonsik Yu
  • Junghoon Joh
  • Junho Song
  • Ki-Young Choi
  • Kim Siyeon
  • Kimiko Yamashita
  • Kiwoon Choi
  • Masahide Yamaguchi
  • Mehedi Masud
  • Minho SON
  • Mitsuru Kakizaki
  • Myeonghun Park
  • Nicolás Bernal
  • Rojalin Padhan
  • Sang Hui Im
  • Satyabrata Mahapatra
  • Seodong Shin
  • Seokhoon Yun
  • Seong Moon Yoo
  • Seongsik Kim
  • Seung J. Lee
  • Shu-Yu Ho
  • Shuntaro Aoki
  • Sin Kyu Kang
  • Songmin Lee
  • Sung Mook Lee
  • SungBo Sim
  • Sunghyun Kang
  • SungWoo Youn
  • Suruj Jyoti Das
  • Tae Jeong Kim
  • Tomasz Dutka
  • Young-Hwan Hyun
  • Youngjoon Kwon
  • +25
Contact: Prof. Hyun Min Lee
    • Axion
      • 1
        Bubbles and Walls in Axion Cosmology
        Speaker: Prof. Fuminobu Takahashi (Tohoku University)
    • 10:30 AM
      Coffee break
    • Axion
    • 12:00 PM
    • Neutrino / Dark Matter
      • 4
        Common origin of dark matter, baryon asymmetry and neutrino masses in the standard model with extended scalars
        Speaker: Sin Kyu Kang (Seoul-Tech)
      • 5
        Dark matter searches at LHC
        Speaker: Chang-Seong Moon (Kyungpook National University (KR))
      • 6
        Probing dark Z decays at the HL-LHC using Transformer Encoder
        Speaker: Prof. Myeonghun Park (Seoultech)
    • 3:30 PM
      Coffee break
    • Dark Matter
      • 7
        Dark sector particle searches with NaI(Tl) crystals
        Speaker: Prof. Hyunsu Lee (IBS CUP)
      • 8
        Probing sterile neutirno-tau neutrino mixing at SHiP experiment
        Speaker: Ki-Young Choi (Sungkyunkwan University (KR))
      • 9
        Probing the Migdal effect in the precise angular distribution
        Speaker: Prof. Bin Zhu (Yantai University)
    • Gravitational Waves
    • 10:30 AM
      Coffee break
    • Gravitational Waves
      • 11
        Scalar Field in Black Holes and Interactions

        We introduce the scattering of a scalar field in the black hole spacetime. Based on our recent studies, various sides of a black hole are presented. When a scalar field is scattered by a black hole, there are fluxes going into the black hole. From the fluxes of the scalar field flowing into the black hole, the changes in mass and angular momenta of the black hole are obtained. These can affect the state of the black hole. We analyze the changes in the black hole, and its modifications are discussed.

        Speaker: Bogeun Gwak (Dongguk University)
      • 12
        Ringdown gravitational waves from close scattering of two black holes
        Speaker: Dr Young-Hwan Hyun (KASI)
      • 13
        Detection of high frequency gravitational waves in EM cavities
        Speaker: Dr Sang Hui Im (IBS CTPU)
    • 12:20 PM
    • Axion
      • 14
        Probing the PQ quality with Electric Dipole Moments
        Speaker: Prof. Kiwoon Choi (IBS CTPU)
      • 15
        A Cosmic Window on the Dark Axion Portal
        Speaker: Minho SON
      • 16
        Axion Dark Matters from Cosmic String Network

        Global cosmic string simulation is revisited on the lattice of the size of 4096^3. The simulation result supports the recently observed logarithmic growth in both the string number density and the power-law spectral index for the instantaneous axion emission spectra from string. It is found that these results stay robust against various simulation setups differing by the initial conditions and whether the field is thermal or not. A possible correlation between the spectral index and the string number density is discussed as well. Additionally, a new novel string identification method is introduced, which guarantees the connectedness of the strings and provides a convenient way of assigning core location.

        Speaker: Heejoo Kim (KAIST)
    • 3:30 PM
      Coffee break
    • Higgs
      • 17
        The Weak Scale Circa 2024: Crisis of Naturalness, or of Aesthetics? (zoom)

        Zoom talk
        Time: Feb 20, 2024 04:00 PM Seoul


        Meeting ID: 834 4621 6531
        Passcode: CAUBSM

        Speaker: Matthew Philip Mccullough (CERN)
      • 18
        The latest results from the LHC
        Speaker: Tae Jeong Kim (Hanyang University (KR))
      • 19
        Geometric view for the pNGB potential

        We investigate the pseudo-Nambu-Goldstone bosons (pNGBs) potential in the geometrical point of view. In this talk, first I will review about spontaneous symmetry breaking and NGB and how to construct the effective Lagrangian. Then I will discuss about pNGB with explicit symmetry breaking and how to essentially organise or structurally understand the pNGB potential without recourse to the UV symmetries.

        Speaker: Dongwoo Kang
    • Dark Matter
      • 20
        Current status of dark matter and cosmology
        Speaker: Nicolás Bernal (New York University Abu Dhabi)
    • 10:30 AM
      Coffee break
    • Dark Matter
      • 21
        The baryon asymmetry from a scale hierarchy
        Speaker: Chang Sub Shin (Institute for Basic Science)
      • 22
        BBN constraint on majoron

        In this talk, I will introduce the Big Bang nucleosynthesis (BBN) constraint on the majoron-like particle in the mass range between 1MeV to 10GeV which dominantly decays into the standard model neutrinos. For a lifetime shorter than 1 sec, the majoron heats up the background plasma by injecting neutrinos and changes the relation of photon temperature and background neutrino temperature, resulting in a deficit of 4He abundance and an enhancement of deuterium abundance. When the majoron lifetime is longer than 1 sec, the injected neutrinos directly convert protons to neutrons, and consequently, the deuterium becomes overabundant. In both cases, the overabundance of deuterium provides the strongest constraint and it excludes the parameter range where the 7Li abundance can be explained. We also estimate other cosmological constraints and compare them with the BBN bound.

        Speaker: Dr Tae Hyun Jung (Institute for Basic Science)
      • 23
        Halo-independent bounds of WIMP-nucleon couplings from direct detection and neutrino observations in elastic and inelastic scatterings

        I will discuss the halo-independent bounds on the WIMP-nucleon couplings of the non-relativistic effective Hamiltonian that drives the scattering process off nuclei of a WIMP of spin 1/2 combining direct detection experiments and neutrino telescopes data in order to cover the full WIMP incoming speed range.
        In the elastic interactions, for most of the couplings the degree of relaxation of the halo-independent bounds compared to those obtained with the Standard Halo Model is relatively moderate in the low and high WIMP mass regimes while in the intermediate mass range it can be large. An exception with moderate bounds at all WIMP masses is observed in the case of several WIMP-proton couplings that depend on the nuclear spin and on the WIMP incoming velocity.
        In the case of inelastic scattering, I show that a non-vanishing mass splitting modifies incoming WIMP speed range and that for particular combinations of WIMP mass and mass splitting the complementarity between two detection techniques is lost. In low-mass regime the neutrino telescope bound is sufficient alone to provide a halo-independent constraint. On the other hand at large WIMP masses the halo-independent bound is given by a combination of two kinds of experiments.

        Speaker: Sunghyun Kang (Sogang University)
    • 12:20 PM
    • Inflation
      • 24
        Lattice Cosmology

        We will introduce 'Lattice Cosmology' techniques and explain how these can be used to solve non-linear dynamics of interactive fields in an expanding Universe. As a demonstration of these ideas we apply them to solve three different problems of early Universe cosmology: i) the non-linear dynamics of axion inflation, iii) the dynamics and gravitational wave emission of string loops, and if time permits, iii) the non-linear dynamics of non-minimally coupled scalars.

        Speaker: Daniel G. Figueroa (Univ. of Valencia and CSIC (ES))
      • 25
        High-Frequency Gravitational Waves in Axion Haloscopes
        Speaker: Sung Mook Lee (Yonsei University (KR))
    • 3:30 PM
      Coffee break
    • Inflation
      • 26
        The fall and the rise of Weyl gauge theory (zoom)

        Zoom talk
        Time: Feb 21, 2024 04:00 PM Seoul


        Meeting ID: 823 9818 9490
        Passcode: CAUBSM

        Speaker: Dumitru Ghilencea (Horia Hulubei National Institute of Physics and Nuclear Engineering (RO))
      • 27
        Imprint of inflationary gravitational waves and WIMP dark matter in pulsar timing array data

        Motivated by the recent release of new results from five different pulsar timing array (PTA) experiments claiming to have found compelling evidence for primordial gravitational waves (GW) at nano-Hz frequencies, we consider the prospects of generating such a signal from inflationary blue-tilted tensor power spectrum in a specific dark matter (DM) scenario dubbed as Miracle-less WIMP. While Miracle-less WIMP, due to insufficient interaction rate with the Standard Model (SM) bath gets thermally overproduced, inflationary blue-tilted gravitational waves (BGW) in compliance with PTA data, conflict cosmological observations if reheat temperature after inflation is sufficiently high. Both these issues are circumvented with late entropy dilution, bringing DM abundance within observational limits and creating a doubly-peaked feature in the BGW spectrum consistent with cosmological observations. The blue-tilted tail of the low-frequency peak can fit NANOGrav 15 yr data, while other parts of the spectrum are within reach of present and future GW experiments.

        Speaker: Suruj Jyoti Das (Indian Institute of Technology Guwahati)
      • 28
        Higgs pole inflation
        Speaker: Mrs Adriana Guerrero Menkara
    • Inflation
      • 29
        Primordial black holes from inflation
        Speaker: Guillermo Ballesteros (IFT UAM-CSIC)
    • 10:30 AM
      Coffee break
    • Inflation
      • 30
        Euclidean wormholes and the origin of alpha-vacua

        We investigate Euclidean wormholes and their cosmological implications. Generically it was known that the Euclidean compact instantons explain the Bunch-Davies vacuum. If we make the assumption weeker and consider the Euclidean wormholes, we have the freedom to choose another vacuum condition. If we impose the de Sitter invariance condition, we can conclude that the Euclidean wormholes can be the geometrical origin of the alpha-vacua. We will explain technical details in this presentation.

        Speaker: Prof. Dong-han Yeom (Asia Pacific Center for Theoretical Physics)
      • 31
        Gauged Quintessence

        We introduce the gauged quintessence model, in which the dark energy field (quintessence) has a gauge symmetry. This is a kind of realization of the interacting quintessence model and the first quintessence model under a gauge symmetry. We identify the radial part of the complex scalar as the dark energy field (quintessence), while the angular part is the longitudinal component of a new gauge boson. It brings interesting characters to dark energy physics. The
        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. Also, the gauged quintessence model can make possible the misalignment production of relic density of the dark gauge boson.

        Speaker: Jaeok Yi (KAIST)
      • 32
        Non gravitational signals of dark energy under a gauge symmetry

        We investigate non-gravitational signals of dark energy within the framework of gauge symmetry in the dark energy sector. Traditionally, dark energy has been primarily studied through gravitational effects within general relativity or its extensions. On the other hand, the gauge principles have played a central role in the standard model sector and dark matter sector. If the dark energy field operates under a gauge symmetry, it introduces the possibility of studying all major components of the present universe under the same gauge principle. This approach marks a significant shift from conventional methodologies, offering a new avenue to explore dark energy.

        Speaker: Jiheon Lee (KAIST)
    • 12:10 PM
    • Flavor
      • 33
        New physics search via angular distribution of B→D∗ℓν decay in the light of the new lattice data

        A recent theory work on new physics search in the B->D*l nu decay (including Vcb puzzle etc) will be discussed.

        Speaker: Emi Kou (LAL-IN2P3)
      • 34
        Recent highlights from the Belle II experiment
        Speaker: Youngjoon Kwon
      • 35
        Exciting prospects for dark matter at neutrino and direct detection
        Speaker: Prof. Jong-Chul Park (Chungnam National University (KR))
      • 36
        Recent B+ → Kνν Excess, Muon (g − 2) and thermal WIMP DM in U(1)𝑳𝝁−𝑳𝝉 Model

        The Belle II collaboration recently announced that they observed the B+ → K+νν decay process for the first time. This dineutrino mode of B+ → K+νν has been theoretically identified as a very clean channel. However, their result encounters a 2.8σ deviation from the Standard Model (SM) calculation. On the other hand, last year, Fermilab released new data on muon (g − 2) away from the SM expectation with 5σ. In this talk, I will talk about the simplest UV-complete U(1)Lµ−Lτ -charged complex scalar Dark Matter (DM) model. Thanks to the existence of light dark Higgs boson and light dark photon, we can explain the observed relic density of DM and resolve the results reported by both Belle II and Fermilab experiments simultaneously without any modification of the thermal history of the Universe. As a byproduct, the Hubble tension is alleviated taking ∆Neff ≃ 0.3 induced by light Z′.

        Speaker: Dr Jongkuk Kim (Korea Institute for Advanced Study)
    • Discussion
    • 6:00 PM

      Project A, Glad Hotel, Yeouido

    • Inflation
      • 37
        New Dynamical Degrees of Freedom from Invertible Transformations
        Speaker: Masahide Yamaguchi (Tokyo Institute of Technology)
      • 38
        Inflationary Correlators with Dynamical Mass

        Massive fields can imprint unique oscillatory features on primordial correlation functions or inflationary correlators, which is dubbed the cosmological collider signal. In this work, we analytically investigate the effects of a time-dependent mass of a scalar field on inflationary correlators, extending previous numerical studies and implementing techniques developed in the cosmological bootstrap program. The time-dependent mass is in general induced by couplings to the slow-roll inflaton background, with particularly significant effects in the case of non-derivative couplings. The obtained formulae are utilized to discuss the phenomenological impacts on the power spectrum and bispectrum, and it is found that the scaling behavior of the bispectrum in the squeezed configuration, i.e., the cosmological collider signal, is modified from a time-dependent Boltzmann suppression. By investigating the scaling behavior in detail, we are in principle able to determine the non-derivative couplings between the inflaton and the massive particle.

        Speaker: Shuntaro AOKI
    • 10:30 AM
      Coffee break
    • Dark Matter
      • 39
        Lessons from the bygone anomalies : Personal viewpoints
        Speaker: Prof. Pyungwon Ko (KIAS (Korea Institute for Advanced Study))
      • 40
        Hunting for Hypercharge Anapole Dark Matter

        We conduct a combined analysis to investigate dark matter (DM) with hypercharge anapole
        moments, focusing on scenarios where Majorana DM particles with spin 1/2 or 1 interact
        exclusively with Standard Model particles through U(1)Y hypercharge anapole terms. For
        completeness, we construct general, effective, and hypercharge gauge-invariant three-point
        vertices. These enable the generation of interaction vertices for both a virtual photon γ and
        a virtual Z boson with two identical massive Majorana particles of any non-zero spin s, after
        the spontaneous breaking of electroweak gauge symmetry. For complementarity, we adopt an
        effective operator tailored to each dark matter spin allowing crossing symmetry. We calculate
        the relic abundance, analyze current constraints and future sensitivities from dark matter
        direct detection and collider experiments, and apply the conceptual naive perturbativity
        bound. Our findings demonstrate that the scenario with spin-1 DM is more stringently
        constrained than that with spin-1/2, primarily due to the reduced annihilation cross-section
        and/or the enhanced rate of LHC mono-jet events. A significant portion of the remaining
        parameter space in the spin-1/2 DM scenario can be explored through upcoming Xenon
        experiments, with more than 20 ton-year exposure equivalent to approximately 5 years of
        running the XENONnT experiment. The spin-1 scenario can be almost entirely tested after
        the full run of the high-luminosity LHC, except for a very small parameter region where the
        DM mass is around 1 TeV. Our estimations, based on a generalized vertex, anticipate even
        stronger bounds and sensitivities for Majorana dark matter with higher spins.

        Speaker: Jaehoon Jeong (KIAS)
    • 12:00 PM
    • Neutrino / Dark Matter
      • 41
        Uncovering Secret Neutrino Interactions at Tau Neutrino Experiments
        Speaker: Prof. Seodong Shin (Jeonbuk National University)
      • 42
        Bounds to dark photon model from invisible and semi-invisible meson decays

        Invisible and semi-invisible decays of mesons are good tools for testing dark matter models. In particular, we consider the possibility to study dark photon model parameter space in experiments at fixed target (for NA64 and other). We discuss limits from fixed target experiments using leptonic or hadronic beams.

        Speaker: Alexey Zhevlakov (Joint Institute for Nuclear Research (RU))
      • 43
        Searching for Heavy Leptophilic $Z'$ at the Future Lepton Colliders

        We study the phenomenology of leptophilic $Z'$ gauge bosons at the future high-energy $e^+e^-$ or $\mu^+\mu^-$ colliders. The leptophilic $Z'$ model remains largely unconstrained from current low-energy and collider searches for $Z'$ masses above ${\cal O}(100~{\rm GeV})$, thus providing a unique opportunity for future lepton colliders. Taking leptophilic $U(1)_{L_\alpha-L_\beta}~(\alpha,\beta=e,\mu,\tau)$ models as concrete examples, we show that future $e^+e^-$ and $\mu^+\mu^-$ colliders with multi-TeV center-of-mass energies provide unprecedented sensitivity to heavy $Z'$ bosons.

        Speaker: Ms ROJALIN PADHAN (Institute of Physics, Bhubaneswar)
    • 3:10 PM
      Coffee break
    • Dark Matter
      • 44
        Light thermal dark matter via type-I seesaw portal

        We propose a minimal scenario for light thermal dark matter (DM) in sub-GeV to GeV ballpark by incorporating a scalar singlet DM in a type-I seesaw scenario extended by an additional Higgs doublet ϕ2. The latter permits efficient annihilation of light scalar DM into leptonic final states including right-handed neutrinos (RHN). While DM annihilation into charged lepton final states is kept either suppressed or in a kinematically forbidden ballpark to avoid cosmic microwave background (CMB) bounds, the RHN, active neutrino final states remain safe from such bounds even if they are allowed kinematically. We discuss the interplay of forbidden and non-forbidden channels in generating light thermal DM relic while incorporating constraints from cosmology as well as laboratory experiments. The model can also explain the anomalous magnetic moment of muon, W-mass anomaly and saturate experimental bounds on charged lepton flavour violation and DM direct detection while offering tantalising detection prospects of the lightest RHN, the mass of which is kept in the same ballpark as DM.

        Speaker: Satyabrata Mahapatra (Sungkyungkwan University)
      • 45
        WIMPs in Dilatonic Einstein Gauss-Bonnet Cosmology

        In this talk I will discuss how the Weakly Interacting Massive Particle (WIMP) thermal decoupling scenario can be used to probe Cosmologies in dilatonic Einstein Gauss-Bonnet (dEGB) gravity, where the Gauss–Bonnet term is non–minimally coupled to a scalar field with vanishing potential. Constraints on the model parameters can be obtained when the ensuing modified cosmological scenario drives the thermal WIMP annihilation cross-section beyond the present bounds from dark matter indirect detection searches. In the presentation I will assume WIMPs that annihilate to Standard Model particles through an s-wave process. I will also show that the bounds from WIMP indirect detection are nicely complementary to late-time constraints from compact binary mergers. This suggests that it could be interesting to use other Early Cosmology processes to probe the dEGB scenario.

        Speaker: Arpan Kar (Center for Quantum Spacetime (CQUeST), Sogang University)