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KEK Theory Meeting on Particle Physics Phenomenology (KEK-PH2025winter)

Feb 18 – 21, 2025
Building 3
Asia/Tokyo timezone

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Contribution List

71 / 71
1. opening
2/18/25, 10:00 AM
4. CERN Future Circular Collider: an electroweak and flavour factory
Christophe Grojean
2/18/25, 10:10 AM
5. Quantum Entanglement and Emerging Symmetry
Ian Low
2/18/25, 11:10 AM
6. Recent results from ATLAS and prospects for HL-LHC
Shigeki Hirose
2/18/25, 1:30 PM
7. Recent results in MLPhys --- "Machine Learning Physics" initiative in Japan
Koji Hashimoto
2/18/25, 2:10 PM
25. Evanescent contribution of the QCD theta angle
Naohiro Osamura
2/18/25, 3:20 PM

In this talk, we evaluate the QCD theta angle radiatively induced at the two-loop level using the dimensional regularization with the BMHV scheme in a simplified model. When the Lagrangian is promoted into d-dimensional space through the dimensional regularization, evanescent operators are introduced, which break the chiral symmetry. Consequently, a parity-odd fermion loop with the BMHV scheme...
19. Flavor anomalies and 2HDM with flavor symmetry
Fanrong Xu
2/18/25, 3:20 PM

Anomalies in b -> s l l and b -> c l nu decays have persisted for over a decade. In this talk, I will explore the current landscape from three perspectives. First, global fits offer a model-independent approach to understanding the latest data. I will present our recent work on global fits incorporating around 200 binned observables, which reveals intriguing indications that new physics may...
26. Spontaneous CP violation in supersymmetric QCD
Yaoduo Wang
2/18/25, 3:40 PM

We investigate a composite model of spontaneous CP violation based on a new supersymmetric QCD as a solution to the strong CP problem. The scalar components of the meson chiral superfields obtain complex vacuum expectation values to break CP symmetry spontaneously. Then, wavefunction renormalization for the quark kinetic terms provides the Cabibbo-Kobayashi-Maskawa (CKM) phase, while the...
20. The possible solution to V_cb puzzle from nontrivial analyticity of quark propagator
Jinglong Zhu
2/18/25, 3:40 PM

There is a longstanding tension between inclusive and exclusive |Vcb| determinations of Cabibbo-Kobayashi-Maskawa matrix element, i.e. Vcb puzzle. In this work, a nontrivial analytical structure of the quark propagator, indicated from the perspective of color confinement, is included for the first time in the inclusive B decay. To discuss the possibility of solving the Vcb puzzle, the...
21. A novel approach to charm mixing
Hiroyuki Umeeda
2/18/25, 4:00 PM

For $D^0-\bar{D}^0$ mixing, it is known that the operator product expansion cannot properly reproduce the order of magnitude of the experimental data. The difficulty in the conventional method arises from the significant cancellation due to the GIM mechanism. In this work, we analyze mass difference based on the Schwinger-Dyson approach. It is shown that the order of magnitude of the...
27. Does finetuning make D-term contributions smaller in natural grand unified theories with spontaneous supersymmetry breaking?
Taiju Tanii
2/18/25, 4:00 PM

We explore the natural grand unified theory (GUT) with spontaneous supersymmetry
(SUSY) breaking, focusing on the contribution to sfermion and Higgs masses. Natural GUTs, which introduce all terms allowed by SO(10) × U (1)A symmetry with O(1) coefficients, provide a solution to the problems in SUSY GUTs. Although it is also possible to introduce spontaneous SUSY breaking, it predicts D-term...
22. Analysis of Flavor Models by Diffusion Model
Satsuki Nishimura
2/18/25, 4:50 PM

In conventional analyses of flavor models, the search space of parameters is often restricted to a certain range to optimize the parameters of the theory within a realistic computational time. In this talk, we propose an analytical method utilizing a diffusion model, which is a type of generative artificial intelligence. This strategy can be applied independently of the specific details of the...
29. Wiggly dilaton: a landscape of spontaneously broken scale invariance
Yu-Cheng Qiu
2/18/25, 4:50 PM

The dilaton emerges as a pseudo-Nambu-Goldstone boson (pNGB) associated with the spontaneous breaking of scale invariance in a nearly conformal field theory (CFT). We show the existence of a wiggly dilaton potential that contains multiple vacuum solutions in a five-dimensional (5D) holographic formulation. The wiggly feature originates from boundary potentials of a 5D axion-like scalar field,...
28. Gauge symmetry breaking with two dimensional sphere as extra dimensions
Hiroki Ishikawa
2/18/25, 5:10 PM

In the grand unified theory, the Higgs mechanism is commonly used. However, as an alternative approach, extra dimensions with non-zero curvature can lead to gauge symmetry breaking.

We have constructed a Yang-Mills theory with extra dimensions as two-dimensional sphere(S^2). As a result, the curvature of the extra dimensions and the non-commutative nature of the gauge group lead to a...
23. Heavy quark symmetry behind b → c semileptonic sum rule
Syuhei Iguro
2/18/25, 5:10 PM

Lepton flavor universality violations in semileptonic b→c transitions have garnered attention over a decade. For RH_c=BR(H_b→H_cτν)/BR(H_b→H_cℓν) with ℓ being e, μ, a sum rule among RD, RD∗ and RΛc was proposed to check consistency in the experimental results independently of new physics models. We revisit this relation from the perspective of the heavy quark symmetry. We derive a sum rule...
30. Mass spectrum of the extra-dimensional components of gauge fields in Yang-Mills theory with extra dimensions of two-dimensional sphere
Yuki Honda
2/18/25, 5:30 PM

The theoretical origin of the Higgs boson remains unclear. Yang-Mills theories in higher dimensions are good candidates to address this issue.
We have constructed a Yang-Mills theory with extra dimensions of two-dimensional sphere. In this model, compared to conventional models such as those with S^1 and T^2, curvature of the extra dimensions and the non-commutative nature of the gauge group...
8. Majorana phases beyond neutrinoless double beta decay
Zoltan Ligeti
2/19/25, 9:00 AM
9. Recent updates and future prospects of the Belle II experiment
Abner Soffer
2/19/25, 9:40 AM

I will report recent results and prospects for future results from the Belle II experiment
10. Flavor Patterns of Fundamental Particles from Quantum Entanglement?
Sokratis Trifinopoulos
2/19/25, 10:30 AM

The Cabibbo-Kobayashi-Maskawa (CKM) matrix, which controls flavor mixing between the three generations of quark fermions, is a key input to the Standard Model of particle physics. In this paper, we identify a surprising connection between quantum entanglement and the degree of quark mixing. Focusing on a specific limit of 2→2 quark scattering mediated by electroweak bosons, we find that the...
11. Direct Dark Matter Detection with Liquid Xenon Detectors
Shingo Kazama
2/19/25, 11:10 AM
39. Photon Proliferation Effect from N-body ultralight DM annihilation
Shaoping Li
2/19/25, 1:30 PM

I will demonstrate a general photon proliferation effect from N-body ultralight dark matter (DM) annihilation in the early Universe, which can induce a drastic photon-temperature shift after neutrino decoupling. For pseudoscalar DM mass below the eV scale, I will show that the photon proliferation effect becomes significant as the mass approaches the ultralight end, presenting the leading...
31. Single top plus Higgs production at the LHC
Yajuan Zheng
2/19/25, 1:30 PM

We study the single top plus Higgs production process at the LHC with a CP violating Yukawa coupling from a dimension-6 operator. The amplitude of the subprocess ub>dtH is obtained both in the Unitary (U) and Feynman-Diagram (FD) gauges. Energy and angular distributions of the cross section and CP violating asymmetries are understood from the interference among the FD gauge amplitudes.
40. Composite Dark Matter with Forbidden Annihilation
Takumu Yamanaka
2/19/25, 1:50 PM

A dark matter model with QCD-like SU(N) gauge symmetry and electroweakly interacting dark quarks is discussed. In this model, the lightest G-parity odd dark pion is a main component of dark matter. I will discuss the relation between the mass spectrum of dark pions and annihilation channels which mainly contribute to the relic abundance. When the masses of dark matter and heavier dark pions...
32. Transformers for jet tagging
Ahmed Hammad
2/19/25, 1:50 PM

Attention-based transformer models have become increasingly prevalent in collider analysis, offering enhanced performance for tasks such as jet tagging. However, they are computationally intensive and require substantial data for training. we introduce a new jet classification network using an MLP mixer, where two subsequent MLP operations serve to transform particle and feature tokens over...
33. Dark photon pair production via off-shell dark Higgs at FASER
Yohei Nakashima
2/19/25, 2:10 PM

We consider a dark photon model in which the dark U(1) gauge symmetry is spontaneously broken by a vacuum expectation value of a new scalar boson. We focus on the ForwArd Search ExpeRiment (FASER) and calculate its sensitivity to the dark photon produced from the off-shell decay of the new scalar boson. It is found that the off-shell production extends the sensitivity region beyond the...
41. pseudo-Nambu-Goldstone-boson as a Dark Matter Candidate: A Model with Three Complex Scalars under Z3 Symmetry
Riasat Sheikh
2/19/25, 2:10 PM

This study explores a dark matter model where the pseudo-Nambu-Goldstone boson (pNGB) emerges as a viable candidate, resulting from the spontaneous breaking of a U(1) symmetry and stabilized by a Z3 discrete symmetry which naturally emerges as a residual symmetry. The model introduces three complex scalar fields invariant under Standard Model (SM) gauge symmetries, naturally suppressing direct...
42. Excited bound states and their role in dark matter production
Stefan Lederer
2/19/25, 3:00 PM

I explore the impact of highly excited bound states on the evolution of number densities of new physics particles, specifically dark matter, in the early Universe.

Higher excited states play a crucial role in non-Abelian interactions, going as far as preventing a complete decoupling in the early Universe and thus preventing the constituent particle from freezing out. Instead, a continuous...
34. T violation at a future neutrino factory
Sho Sugama
2/19/25, 3:00 PM

We study the possibility of measuring T (time reversal) violation in a future long baseline neutrino oscillation experiment. By assuming a neutrino factory as a staging scenario of a muon collider at the J-PARC site, we find that the ν_e → ν_μ oscillation probabilities can be measured with a good accuracy at the Hyper-Kamiokande detector. By comparing with the probability of the time-reversal...
43. Black String in the Standard Model
Hayate Kimura
2/19/25, 3:20 PM

We found black string solutions in the 4 dimensional standard model, whose existence is suggested by swampland conjecture. The well-known no-go theorem for topologies of horizon except two sphere is avoided by taking into account the Casimir energy, which violate the dominant energy condition, in the energy-momentum tensor.
35. Higgs Boson Production at µ^+ µ^+ Colliders
Lukas Treuer
2/19/25, 3:20 PM

Motivated by recent advancements in antimuon cooling, we study Higgs boson production at µ^+ µ^+ colliders at high energy. Since both initial-state particles are positively charged, there is no W boson fusion at the leading order, as it requires a W^+ W^− pair. However, we find that the cross section of the higher-order, γ- and Z-mediated W boson fusion process is large at high center-of-mass...
44. Realising Dark Matter and PTA via Dark Branes
Fotis Koutroulis
2/19/25, 3:40 PM

In this work we propose a setup for the origin of dark matter based on spacetime with a warped extra dimension and three branes: the Planck brane, the TeV brane and a dark brane, at a (sub)-GeV scale. The Standard Model is localized in the TeV brane, thus solving the Higgs hierarchy problem, while the dark matter χ, a Dirac fermion, is localized in the dark brane. The dark matter has only...
36. Verifying the Resonance Schemes of Unstable Particles at Lepton Colliders
Ui Min
2/19/25, 3:40 PM

We propose practical ways of differentiating the various (Breit-Wigner, theoretical, and energy-dependent) resonance schemes of unstable particles at lepton colliders. First, the energy-dependent scheme can be distinguished from the other two by fitting the Z lineshape scan and forward-backward asymmetries at LEP and future lepton colliders with the Z mass mZ, decay width ΓZ, and coupling...
45. Minimal dark matter in SU(5) grand unification
Takashi Toma
2/19/25, 4:30 PM

Minimal dark matter is an attractive candidate for dark matter because it is stabilized without the need to impose additional symmetries. It is known that the mass of the SU(2)L quintuplet fermion dark matter is predicted to be around 14 TeV, based on the thermal production mechanism. In this work, we embed the quintuplet dark matter within non-supersymmetric SU(5) grand unified theories. We...
37. Prospects for quantum process tomography at high energies
Kazuki Sakurai
2/19/25, 4:30 PM

In quantum information theory, the evolution of an open quantum system -- a unitary evolution with the environment followed by a measurement -- is described by a Quantum Channel or, more generally, a Quantum Instrument. In this talk, I will formulate spin and flavour measurements in collider experiments as a Quantum Instrument. We demonstrate that the Choi matrix, which completely determines...
38. New Physics Implications of Vector Boson Fusion Searches
Nivedita Ghosh
2/19/25, 4:50 PM

LHC searches for nonstandard scalars in vector boson fusion (VBF) production processes can be particularly efficient in probing scalars belonging to triplet or higher multiplet representations of the Standard Model SU(2)L gauge group. They can be especially relevant for models where the additional scalars do not have any tree-level couplings to the Standard Model fermions, rendering VBF as...
46. Phenomenology of Neutrino-Dark Matter Interaction in DSNB and AGN
Po-Yen Tseng
2/19/25, 4:50 PM

We introduce a neutrino-scalar dark matter (DM) ν-ϕ interaction and consider Diffuse Supernova Neutrino Background (DSNB) and Active Galactic Nuclei (AGN) representing distinctive neutrino sources. We focus on interaction mediated by a heavy fermionic particle F and investigate the attenuation of neutrino fluxes from these sources. We model the unscattered neutrino flux from DSNB via...
24. Are Fractals Behind Flavor Mixing of the SM?
Aadarsh Singh
2/19/25, 5:10 PM

We explore the idea that the underlying flavour structure of the Standard Model could be determined by a fractal geometry. We consider theory space on a Sierpenski-like geometry. Fermion mass chains on Sierpinski-like geometry with three decorations(iterations) lead to three zero modes, which can be identified with three generations of the Standard Model. A single parameter expansion for each...
47. Composite asymmetric dark matter with a dark photon portal: Multi-Messenger tests
Takumi Kuwahara
2/19/25, 5:10 PM

Composite asymmetric dark matter (ADM) is the framework that naturally explains the coincidence of the baryon density and the dark matter density of the Universe. Through a portal interaction sharing particle-antiparticle asymmetries in the Standard Model and dark sectors, dark matter particles, which are dark-sector counterparts of baryons, can decay into antineutrinos and dark-sector...
12. Dark Matter Detection using Quantum Bits
Takeo Moroi
2/20/25, 9:00 AM

I will discuss a possibility to use quantum bits (qubits) for wave-like-dark-matter detection. I will explain the basic idea and show the expected sensitivity. I will also discuss an idea to enhance the sensitivity using quantum nature of the qubits.
13. Soft Collinear Effective Theory for heavy dark matter annihilation
Motoko Fujiwara
2/20/25, 9:40 AM

Electroweakly interacting stable particles in the (1 − 10) TeV mass range can be a dark matter candidate with rich testability.
In particular, gamma-ray line-like features are expected to be a smoking-gun signature for indirect detection.
In this framework, one fundamental question follows; how to distinguish DM spin among DM candidates with the same electroweak interaction by contrasting...
14. Undulators as axion factories
Wen Yin
2/20/25, 10:30 AM

I will present a low-cost experimental proposal for axion searches at synchrotron radiation facilities, such as SPring-8, NanoTerasu, and Photon Factory. Specifically, I will discuss the method for calculating axion production in an undulator, a type of light source widely used across various fields. By positioning an axion detector outside the shield used in the primary experiments, we can...
15. Cosmic Microwave Background
Akito Kusaka
2/20/25, 11:10 AM
57. Lepton Flavor Violating Decay of True Muonium
Ryotaro Minato
2/20/25, 1:30 PM

Lepton Flavor Violation (LFV) serves as a crucial probe into physics beyond the Standard Model. To identify the new particles behind LFV, it is important to search for various types of LFV processes, because the LFV mediators indirectly appear in most of LFV processes.
In this study, we propose a new LFV process, the decay of a muon-antimuon bound state into an electron-antimuon (or...
48. Sterile neutrino dark matter production in lepton asymmetric universe and its observational implications
Kentaro Kasai
2/20/25, 1:30 PM

Sterile neutrino with masses of the keV scale is a fascinating candidate for dark matter. In particular, in the presence of significant lepton asymmetry in the standard model neutrino sector in the early universe, resonantly produced sterile neutrinos can explain all dark matter consistent with all the observational constraints. Such a large lepton asymmetry has also been suggested by recent...
58. Axion detection with quantum Hall effect
Aiichi Iwazaki
2/20/25, 1:50 PM

A detailed examination of the plateau transition in the quantum Hall effect reveals the presence of axion influence. In quantum Hall effect experiments, strong magnetic fields are used, and microwaves generated by axions from the surrounding metallic walls are emitted. These microwaves are absorbed by localized electrons, causing them to transition to a delocalized state and contribute to the...
50. New EDM bounds for electroweak baryogenesis with the minimal setup for CP violation in the extended Higgs model
Yushi Mura
2/20/25, 1:50 PM

Electroweak baryogenesis is a promising baryogenesis scenario, which can be tested in various future experiments.
In the mechanism of electroweak baryogenesis, new sources of the CP violation are needed to generate the baryon asymmetry of the Universe.
This new CP violation can be explored in the current and future electric dipole moment (EDM) experiments.
In this talk, we classify the CP...
59. High frequency gravitons from inflation
Kazunori Nakayama
2/20/25, 2:10 PM

We show that gravitons are efficiently produced through various processes during reheating. The detection of ultra high frequency stochastic gravitational waves can directly determine the inflaton mass, decay rate etc.
72. Memory-Burdened Primordial-Black-Hole Dark Matter probed by Induced Gravitational Waves
Takahiro Terada
2/20/25, 2:10 PM

Quantum evaporation of a black hole is conventionally studied semiclassically by assuming self-similarity of the black hole throughout the evaporation process. However, its validity was recently questioned, and the lifetime of a black hole is conjectured to be much extended by the memory burden effect. It gives rise to the possibility that the primordial black holes (PBHs) lighter than 10^10...
51. A new mechanism for leptogenesis in three-Higgs-doublet models
Hidenaga Watanabe
2/20/25, 3:00 PM

In standard leptogenesis, several conditions must be satisfied to produce the observed baryon asymmetry: weak wash-out, CP violation in the neutrino Yukawa couplings, and a heavy Majorana mass.
We propose a new mechanism for leptogenesis that relaxes these conditions by employing three-Higgs-doublet models. The non-thermal decay of an additional heavy Higgs generates a charge asymmetry, which...
60. Impact of the Electroweak Weinberg Operator on the Electric Dipole Moment of Electron
Kiyoto Ogawa
2/20/25, 3:00 PM

The electric dipole moments (EDM) of electron, an observable sensitive to CP violation, is expected to plobe physics beyond the Standard Model (BSM) at TeV scale due to significant improvements in experimental precision. In this study, we evaluated the CP-violating dimension-6 operator for electroweak bosons (the electroweak Weinberg operator) generated at the two-loop level by CP-violating...
61. Constraints on Trilinear Higgs Couplings Including One-loop Correction in Nearly Aligned Higgs Models
Shuhei Ohzawa
2/20/25, 3:20 PM

Although the Higgs boson has been discovered, the couplings between the Higgs boson and Standard Model (SM) particles may deviate from the predictions of the SM. Such deviations can be realized by extending the SM. One possible extension involves the introduction of an extended Higgs model, which extends the Higgs sector. Among extended Higgs models, the nearly aligned Higgs model,...
52. Leptogenesis and Neutrinoless Double-Beta Decay
Tatsuya Yokoyama
2/20/25, 3:20 PM

We revisit the thermal leptogenesis based on the Type I seesaw mechanism and discuss the constraints from future neutrino experiments. Taking the flavor effects into account, we study the influence of the Majorana phases and the effective neutrino Majorana mass for neutrinoless double-beta decay. We present the lower bounds of the right-handed neutrino mass on a plane consisting of the...
53. Leptogenesis in the presence of density perturbations
Rin Takada
2/20/25, 3:40 PM

I point out a new effect on the freeze-out process of heavy particles induced by density perturbations in the early universe.
Already at moderately large density perturbations $\delta T / \bar{T} \sim 10^{-2}$, this effect cannot be captured by linear perturbation theory.
I illustrate this effect with leptogenesis and discuss phenomenological implications.
I consider the simplest case of...
62. New Constraints on Gauged U(1)Lμ-Lτ Models via Z-Z' Mixing
Coh Miyao
2/20/25, 3:40 PM

Models based on a U(1)$_{L_\mu-L_\tau}$ gauge symmetry can explain the discrepancy between the measured value and theoretical prediction of the muon anomalous magnetic moment. Based on the latest experimental results, we revisit the analysis of neutrino mass matrix structures in minimal U(1)$_{L_\mu-L_\tau}$ models where the U(1)$_{L_\mu-L_\tau}$ symmetry breaking is caused by a single scalar...
63. Effective field theory for type II seesaw model --symmetric phase v.s. broken phase--
Yoshiki Uchida
2/20/25, 4:30 PM

Effective field theory is an effective approach to parameterizing effects of high energy scale physics in low energy measurements. The two popular frameworks for physics beyond the standard model are the so-called Standard Model Effective Field Theory (SMEFT) and the Higgs Effective Field Theory (HEFT). While the description by the SMEFT deteriorates when the new physics scale is not so high...
54. Flavored leptogenesis in Scotogenic models
Yurika Sekikawa
2/20/25, 4:30 PM

Flavor effect in leptogenesis is an important effect that can potentially change the baryon asymmetry by up to an order of magnitude.
The scotogenic model proposed by Ernest Ma is an attractive and minimally extended model for producing small neutrino masses through radiative corrections in the dark matter sector.
It is also known that the scotogenic model can explain the baryon asymmetry of...
64. The probability for chiral oscillation of Majorana neutrino in Quantum Field Theory
Tomoharu Tahara
2/20/25, 4:50 PM

We derive the probability for chiral oscillation of Majorana neutrinos based on quantum field theory. Since the Hamiltonian under the Majorana mass term does not conserve lepton number, the eigenstates of lepton number change continuously over time. Therefore, the transition amplitude is described by the inner product of the eigenstates of lepton number at the time of the neutrino production...
55. Thermal leptogenesis in SO(10)×U(1) GUT
Kei Shibata
2/20/25, 4:50 PM

In this study, we show that thermal leptogenesis is successful in the natural SO(10) GUT.
When lepton flavor effects are added to thermal leptogenesis, the second-lightest right-handed neutrino contribute non-negligibly. Compared to the mass of the right-handed neutrino predicted by the symmetry of the natural SO(10) GUT, that obtained in this study is about six times smaller than that of...
56. The time evolution of lepton numbers, Majorana (type) phases and the connection to CP violation for leptogenesis
Takuya Morozumi
2/20/25, 5:10 PM

The time evolution of lepton numbers of Majorana neutrinos are sensitive to neutrino masses , the mixing angles , and CP violation at low energy including Majorana phases and Dirac Kobayashi Maskawa type phase. This implies one can theoretically reconstruct all the elements of the effective Majorana mass matrix at low energy using the time evolution of lepton numbers. In this talk, we...
71. Two-sided story of sterile neutrinos: production under X-ray limits
Muping Chen
2/20/25, 5:10 PM

Sterile neutrinos are well-motivated and actively searched for hypothetical neutral particles that would mix with the Standard Model active neutrinos. They are considered prime warm dark matter (DM) candidates, typically when their mass is in the keV range, although they can also be hot or cold DM components.
We discuss in detail the characteristics and phenomenology of sterile neutrinos that...
16. Candidate de Sitter Vacua
Jacob Moritz
2/21/25, 9:00 AM
65. Effects of electroweak phase transition on dark matter relic abundance
Chikako Idegawa
2/21/25, 9:50 AM

The true identity of dark matter (DM) is an unsolved problem in physics. Among the various DM candidates, weakly interacting massive particles (WIMP) are attractive because their abundance can be explained thermally. The WIMP abundance can be estimated using the Boltzmann equation, and particle masses at zero temperature are usually adopted. In this study, we take into account the electroweak...
68. QCD axion from chiral gauge theories
Shonosuke Takeshita
2/21/25, 9:50 AM

We present models of axion based on supersymmetric chiral gauge theories. In these models, the PQ symmetry is spontaneously broken by the non-perturbative dynamics of chiral gauge theory. Thanks to supersymmetry, IR dynamics of the models are calculable. We also present an example of a QCD axion model that is compatible with SU(5) grand unification. To avoid the proton decay constraint and a...
66. Completing the perturbative program for cosmological phase transitions
Philipp Schicho
2/21/25, 10:10 AM

Scale hierarchies are required to reliably describe the thermodynamics of cosmological first-order phase transitions using perturbation theory. At finite temperature, such a hierarchy is provided naturally. One can then use this hierarchy to construct a three-dimensional effective field theory (EFT) that systematically includes thermal resummations to all orders.

Using this EFT setup, I...
69. How viable is a QCD axion near 10 MeV?
Junxuan Xu
2/21/25, 10:10 AM

There has been an attempt to revive the visible QCD axion at the 10 MeV scale
assuming that it exclusively couples to the first-generation quarks and the electron.
This variant of the QCD axion is claimed to remain phenomenologically viable,
partly due to a clever model construction that induces tree-level pion-phobia and exploits uncertainties inherent in the chiral perturbation...
70. High Quality QCD axion via Electric-Magnetic Duality
Shota Nakagawa
2/21/25, 10:30 AM

Axion can solve the strong CP problem dynamically. However, since a global symmetry is expected to be broken explicitly in quantum gravity theory, any extra Peccei-Quinn (PQ) symmetry breaking operator must be suppressed, except for nonperturbative effects of QCD. In this talk, we propose a novel paradigm for the QCD axion with high-quality PQ symmetry on the basis of electric-magnetic duality...
67. Reheating Process after Axion Inflation
Tenta Tsuji
2/21/25, 10:30 AM

In modern cosmology, it is generally assumed that after inflation, the energy of the inflaton is transferred to radiation through a process known as reheating. Axion-like particles (ALPs) have recently emerged as compelling candidates for the inflaton, primarily because their approximate shift symmetry helps preserve the flatness of the inflationary potential.

This study investigates the...
17. Cascade of Energetic SM Particles
Kyohei Mukaida
2/21/25, 11:00 AM
18. The bubble wall velocity in cosmological phase transitions
Jorinde van de Vis
2/21/25, 11:40 AM

Cosmological first order phase transitions are a promising source of gravitational waves, and a possible explanation of the baryon asymmetry and dark matter abundance.
Predicting the phenomenological consequences of such phase transitions requires knowledge of the expansion velocity of the bubbles formed in a phase transition.
In this talk, I will present WallGo, a software package for the...
3. closing
2/21/25, 12:20 PM
49. DM relic abundance via multi-Higgs production in the early universe
Seishi Enomoto

It is widely believed that parameter space for Higgs-portal dark matter which achieves the relic abundance through the thermal freeze-out is already tightly constrained. In this talk, we propose a novel scenario that the multiple Higgs production dramatically change this picture. As a result, the relic abundance of DM can be achieved by heavy Higgs-portal DM of $m_\chi\gtrsim{\cal O}(1)$ TeV...
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