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Jeonghyeon Song (Konkuk U)08/07/2025, 11:10
We investigate strong first-order electroweak phase transitions in the Type-I two-Higgs-doublet model's inverted Higgs scenario (where the 125 Giga-electron Volt Higgs boson is the heavier CP-even scalar), motivated by its potential for electroweak baryogenesis. A comprehensive parameter scan, incorporating current theoretical and experimental constraints (including flavor, Higgs, and...
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Abhishek Roy (CQUeST)08/07/2025, 11:30
We present an extension of the SM involving three triplet fermions, one triplet scalar and one singlet fermion, which can explain both neutrino masses and dark matter. One triplet of fermions and the singlet are odd under a symmetry, thus the model features two possible dark matter candidates. The two remaining even triplet fermions can reproduce the neutrino masses and oscillation parameters...
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Siyao Li (IBS CTPU-CGA)08/07/2025, 11:50
Oscillons are long-lived, spherically symmetric solitons that can arise in real scalar field theories with potentials shallower than quadratic. They are considered to form via parametric resonance during the preheating stage after inflation and serve as localized storagies of the inflaton field’s energy. Due to their extended lifetimes, oscillons may play a significant role in the early...
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Yechan Kim (KAIST)08/07/2025, 12:10
We study a novel leptogenesis scenario with the temperature-dependent mass of heavy Majorana neutrino by the wave dark matter to explain the matter-antimatter asymmetry of the Universe. The leptogenesis happens twice in this scenario: the first leptogenesis occurs above the electroweak scale, while the second leptogenesis occurs below it. The sphaleron process converts the lepton asymmetry to...
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Jianqiao Deng (CUHK)08/07/2025, 16:40
From topological supergravity, we have found that the action for gravitino contains a coupling between the gravitino and a scalar field. By analogy with the Yukawa coupling, we integrate out the gravitino to obtain an effective action for this scalar field, which may furnish a potential microscopic theory for scalar dark matter.
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Sarif Khan (CAU)08/07/2025, 17:00
In this work, we have explored the conversion-driven freeze-out scenario, where the next-to-lightest stable particle (NLSP) sets the dark matter (DM) abundance through
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the process ``NLSP SM $\leftrightarrow$ DM SM". Although DM is produced via
freeze-out mechanism, its interaction strength with the visible sector can
range from weak-scale to feeble-scale couplings. This leads to a vast,... -
Jiheon Lee (KAIST)08/07/2025, 17:20
We investigate dark gauge-mediated supersymmetry breaking with an unbroken U(1) gauge symmetry and a massless dark photon. Messengers charged under both Standard Model and dark gauge groups generate new soft SUSY-breaking terms via gauge kinetic mixing. Large mixing significantly alters superpartner spectra compared to standard GMSB, reduces the μ parameter, and predicts a relatively light...
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Geonwoo Kang (SNU)08/07/2025, 17:40
We present a numerical proof of the concept that the void spin distributions can provide a tight constraint on the amplitude of matter density fluctuation on the scaleof 8 h inverse Mpc (σ8) without being severely deteriorated by the degeneracies of σ8 with cold dark matter density parameter multiplied by the dimensionless Hubble parameter square (Ωcdmh^2), total neutrino mass (Mν) and dark...
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08/07/2025, 18:00
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Yuhang Zhu (IBS CTPU-CGA)09/07/2025, 11:10
Cosmological correlation functions are fundamental observables in early universe cosmology and offer a remarkable window into the fundamental laws that governed the Universe’s earliest moments. In this talk, the speaker will derive a correlator-to-correlator factorisation formula under mild assumptions, establishing a profound relationship between different observables in the context of...
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Perseas Christodoulidis (Ewha Womans U)09/07/2025, 11:30
I will discuss how to construct an open systems EFT for gauge fields and gravity based on recent developments in Schwinger-Keldysh EFTs. I will then apply the EFT to two representative examples: Maxwell theory and inflation.
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Minxi He (IBS CTPU-PTC)09/07/2025, 11:50
The latest observation from ACT on the scalar spectral index $n_s$ on the cosmic microwave background (CMB) favors a larger value than previous results. To account for this, we propose a class of inflation models, dubbed regularized pole inflation, with a regularized second order pole in the kinetic term of the inflaton which can increase $n_s$ and fit the new data. The regularized pole...
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Tomotaka Kuroda (IBS CTPU-CGA)09/07/2025, 12:10
The stochastic formalism is an effective theory of long-wavelength modes that incorporates probabilistic noise from short-wavelength modes as they exit the horizon. This is expected to have non-perturbative properties, particularly useful in the context of primordial black hole (PBH) formation. Indeed, PBHs are formed from large perturbations exceeding a threshold when they re-enter the...
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Hisaaki Shinkai (Osaka Institute of Technology)09/07/2025, 16:40
Independent component analysis (ICA) is a method to extract a set of time-series data using ``statistical independency" of each component. We applied ICA to extract gravitational wave (GW) signals directly from the detector data. Our idea is to extract a coherent signal that is included in multiple detectors and find it by shifting the data set around its arrival time. In this article, we...
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Chan Park (Henan Academy of Science)09/07/2025, 17:00
Modern gravitational wave (GW) detectors primarily utilize electromagnetic waves (EMWs) in the geometric optics regime. Geometric optics is applicable when the wavelength of the EMWs is much shorter than the characteristic scale of spacetime curvature or variations in the medium. In this work, we explore the potential of using EMWs beyond the geometric optics regime for GW detection. To this...
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Ho Ching Luk (CUHK)09/07/2025, 17:20
Numerical simulations of strange quark stars (QSs) are challenging due to the strong density discontinuity at the stellar surface. This issue becomes even more problematic in merger scenarios, as any ejected strange matter droplets also exhibit discontinuous density surfaces. In this work, we perform general-relativistic simulations of binary QS merger and observe the formation of spiral arms...
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Yu-Qi Dong (Lanzhou U)09/07/2025, 17:40
In this talk, we present the discovery of two previously unrecognized gravitational wave polarization modes—namely, shear modes. We explore the polarization structure of gravitational waves in torsionless spacetimes with non-metricity, which constitute one of the most widely studied classes of non-Riemannian geometries. Since gravitational wave polarization modes are characterized by the...
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Sang Pyo Kim (Kunsan Nat'l U)10/07/2025, 11:10
Black holes in the Einstein-Maxwell theory are Reissner-Nordstrom (RN) and Kerr-Newman (KN) black holes. In this talk black holes are studied in the nonlinear electrodynamics (NED) of Plebanski class of the Maxwell scalar and pseudo scalar. These NED black holes exhibit many interesting features and modify the photon propagation.
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Nils Albin Nilsson (IBS CTPU-CGA)10/07/2025, 11:30
Bumblebee gravity is currently a popular topic, and models are ubiquitus in the literature. In this talk, I will first review the current state of the art; then, I will describe a surprising connection between the bumblebee field and dark energy, as well as results from perturbation theory which rules out a large class of models.
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Stephen Angus (Sogang U)10/07/2025, 11:50
The low-energy limit of string theory contains additional gravitational degrees of freedom that are not present in general relativity. Together with the metric, these fields are naturally embedded in the O(D,D)-symmetric framework of double field theory (DFT). First I will explain how the O(D,D) symmetry uniquely prescribes the interactions between the extended gravitational sector and other...
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Theodoros Nakas (IBS CTPU-CGA)10/07/2025, 12:10
We consider higher-order derivative gauge-field corrections that arise in the fundamental context of dimensional reduction of string theory and Lovelock-inspired gravities and obtain an exact and asymptotically flat black-hole solution, in the presence of nontrivial dilaton configurations. Specifically, by considering the gravitational theory of Euler-Heisenberg nonlinear electrodynamics...
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Sunghoon Jung (SNU)10/07/2025, 16:40
De sitter space may have its version of information problem. This may manifest as non-trivial behavior of correlation functions with spatial separation. We study one of wormhole contributions to the two-point function in the 2-dimensional JT gravity. We speculate on the nature of problem and resolution via wormholes.
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Kaloian Lozanov (APCTP)10/07/2025, 17:00
I am going to talk about a scalar field theory with a Minkowski false vacuum and an unbounded (or very deep) true vacuum. We will see compelling evidence that an AdS bubble of vanishing total energy, embedded in asymptotically flat spacetime, generically undergoes a spherical collapse which leads to a space-like curvature singularity after the formation of trapped surfaces and apparent...
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Hocheol Lee (Dongguk U)10/07/2025, 17:20
We investigate the bound on chaos for a charged probe particle in charged, rotating, AdS black hole backgrounds, particularly in the Kerr–Newman–AdS and Kerr–Sen–AdS spacetimes. By analyzing the particle’s radial dynamics near the local extremum of the effective potential, we compute the Lyapunov exponent and examine potential violations of the bound on chaos proposed by Maldacena, Shenker,...
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De-Chang Dai (Nat'l Dong Hwa U, Taiwan)10/07/2025, 17:40
If two particles collide in the vicinity of a black hole horizon, their center of mass energy is practically unlimited, so another black hole with a large mass and thus entropy can be created. The resulting black hole
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can then merge with the original one. If the black hole is created very close to the horizon, its energy will be highly redshifted for ansymptotic observer. However, its... -
Kota Numajiri (YITP, Kyoto U)10/07/2025, 18:00
When quantum fields live in curved spacetime, their behavior is highly sensitive to the choice of vacuum, which reflects the global structure of the background spacetime. Furthermore, their renormalized stress-energy tensor (RSET) requires the introduction of a local higher-order curvature effect, which induces the trace anomaly. These facts highlight that both the global and local properties...
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Sam Wong (CUHK)11/07/2025, 11:10
In this talk, I will discuss recent progress in understanding non-linear tidal responses and gravitational-wave tails in black hole perturbation theory. In the first part, I will present new findings demonstrating that GR black holes possess an infinite number of vanishing non-linear tidal Love numbers. These results are derived systematically using a worldline effective field theory...
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Hyewon Han (Dongguk U)11/07/2025, 11:30
We investigated the quasinormal modes of massless scalar perturbation on a near-extreme accelerating black hole. The accelerating black hole spacetime is described by the Plebański-Demiański metric, which can be characterized by seven physical parameters. We showed that the conformally invariant Klein-Gordon equation can be separated through transformations that remove the conformal factor in...
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Xiao-Mei Kuang (Yangzhou U)11/07/2025, 11:50
The black hole image consists of the black hole shadow, photon ring and accretion construction, whose shape and size reflect the strong field properties of the central black hole. In this talk, I will present the images of both spherically and axially symmetric Horndiski black holes, which exhibit novel features, differentiating those of the Schwarzschild black hole in general relativity.
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Zi-Yu Tang (IBS CTPU-CGA)11/07/2025, 12:10
It is known that the coupling between axions and photons can lead to a superradiant growth and cause electromagnetic (EM) bursts when the coupling constant multiplied with the amplitude of the axion clould is larger than a critical value. In the first-order of the coupling constant, we studied how the existence of an axion cloud influences the distribution of EMs around a Kerr black hole, and...
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Rui Hu (CUHK)
Sterile neutrinos with masses on the eV scale are promising candidates to account for the origin of neutrino mass and the reactor neutrino anomalies. The mixing between sterile and active neutrinos in the early universe could result in a large abundance of relic sterile neutrinos, which depends on not only their physical mass $m_{\mathrm{phy}}$ but also their degree of thermalization,...
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