Yutaka Ookouchi, Kyushu University
Catalytic Creation of Baby Bubble Universe with Small Positive Cosmological Constant
Online (Zoom), indico page, slides (kek.jp only)
In this talk, I will discuss the decay of metastable de Sitter vacua catalyzed by a black hole and a cloud of strings and apply the method to the creation of the four dimensional bubble universe in the five dimensional AdS spacetime. We study the bounce action for the creation and find that the bubble with very small cosmological constant is favored by the catalysis by assuming appropriate mass scales of the black hole and the cloud of strings to reproduce the present energy densities of matter and radiation in the bubble universe.
Jian-Hua Gao, Shandong University, China
[KEK-Keio-YITP joint seminar] The second order anomalous currents from Wigner function approach
Online (Zoom)
Recently, anomalous hydrodynamics has caused extensively concern in relativistic heavy-ion collisions, the condensed matter physics and so on. In this talk, we will present the second order anomalous transport coefficients derived from the Wigner equation for massless spin-1/2 charged fermions near global equilibrium. We can obtain the Wigner function order by order in the power expansion of the vorticity and electromagnetic field. The Wigner function is derived up to the second order from which the non-dissipative charge currents and the stress tensor can be obtained. At the second order, the vector and axial Hall currents can be induced along the direction orthogonal to the vorticity and electromagnetic field; the charge and energy densities and the pressure have contributions from the vorticity and electromagnetic field. In our method, all the conservation laws are satisfied automatically. We also discuss the trace anomaly in the stress tensor.
Norimi Yokozaki, KEK
SUSY models for muon g-2, and lepton flavor violations
Online (Zoom) https://kds.kek.jp/indico/event/34603/
We consider supersymmetric (SUSY) models for the muon g-2 anomaly, without flavor violations at the tree level. The models can avoid the stringent LHC constraints, and can explain the observed dark matter nature as well. Although the models do not induce too large flavor violating processes within the framework of minimal SUSY standard model, once we adopt a seesaw model to explain the smallness of neutrino masses and the observed baryon asymmetry through thermal Leptogenesis, lepton flavor violating (LFV) processes such as $¥mu ¥to e ¥gamma$ and $¥mu ¥to e$ conversion are likely to be detected at future LFV experiments.
Hidehiko Shimada,YITP, Kyoto University
Bose-Einstein Condensation and large-N colour confinement
Online (Zoom) https://kds.kek.jp/indico/event/34523/ I will discuss my recent work arXiv:2001.10459 with Masanori Hanada(Southampton) and Nico Wntergerst(Niels Bohr Institute).
I will discuss my recent work arXiv:2001.10459 with Masanori Hanada(Southampton) and Nico Wntergerst(Niels Bohr Institute).
In that work we have pointed out that colour confinement in large-N gauge theory and Bose-Einstein condensation (BEC) share basic characteristic features, order paramters, and the basic mechanism. Thus, at a basic level, BEC and large-N confinement may be considered as the same phenomenon, the only difference being that of the gauge symmetry group, S_N for BEC and SU(N) for confinement.
Naoto Kan, Tokyo Institute of Technology
[KEK-Keio-YITP joint seminar] From 3d dualities to hadron physics
Online (Zoom)
When one of the space-time dimension is compactified on S1, the QCD exhibits the chiral phase transition at some critical radius. When we further turn on a background θ term which depends on the S1 compactified coordinate, a topological ordered phase appears at low energy via the winding of θ. We discuss what kind of theories can describe the physics near the critical point by requiring the matching of topological field theories in the infrared. As one of the possibilities, we propose a scenario where the ρ and ω mesons form a U(Nf) gauge theory near the critical point. In the phase where the chiral symmetry is restored, they become the dual gauge boson of the gluon related by the level-rank duality between the three dimensional gauge theories, SU(N)Nf and U(Nf)−N.
Hiroki Matsui, KEK
[cosmophys seminar] Swampland Constraints on No-Boundary Quantum Cosmology
Online (Zoom) The Hartle-Hawking no-boundary proposal describes quantum creation of the universe
The Hartle-Hawking no-boundary proposal describes quantum creation of the universe
from “nothing” with geometry of zero size. We will demonstrate the incompatibility
of the no-boundary proposal and the Swampland conjectures such as (refined) dS conjecture
and distance conjecture. When we take the (refined) dS conjecture seriously,
even the classical universe (more precisely, the saddle-point solution) is not guaranteed.
Even if we somehow relax the conjectures to be consistent with the inflationary paradigm,
the probability of the classical inflationary universe is negligibly small and not consistent
with our observations.
Teppei Kitahara, KMI, Nagoya University
Direct CP violation in $K ¥to ¥mu^+ ¥mu^-$ and new physics search
Online (Zoom) https://kds.kek.jp/indico/event/34562/ A rare decay $K_L ¥to ¥mu^+ ¥mu^-$ has been measured precisely, while a similar rare decay $K_S ¥to ¥mu^+ ¥mu^-$ has not been seen yet, which will be measured by an upgrade of the LHCb experiment. Although both processes are almost CP conserving, I will point out that an interference contribution between $K_L$ and $K_S$ in a neutral kaon beam emerges from a genuine direct CP violation. It will be shown that the interference contribution can be a comparable size to the standard-model prediction of BR$(K_S ¥to ¥mu^+ ¥mu^-)$. I will also introduce several new physics effects in $K ¥to ¥mu^+ ¥mu^-$, and a connection with $¥epsilon’/¥epsilon$, which is a direct CP violation in $K ¥to ¥pi ¥pi$.
A rare decay $K_L ¥to ¥mu^+ ¥mu^-$ has been measured precisely, while a similar rare decay $K_S ¥to ¥mu^+ ¥mu^-$ has not been seen yet, which will be measured by an upgrade of the LHCb experiment. Although both processes are almost CP conserving, I will point out that an interference contribution between $K_L$ and $K_S$ in a neutral kaon beam emerges from a genuine direct CP violation. It will be shown that the interference contribution can be a comparable size to the standard-model prediction of BR$(K_S ¥to ¥mu^+ ¥mu^-)$. I will also introduce several new physics effects in $K ¥to ¥mu^+ ¥mu^-$, and a connection with $¥epsilon’/¥epsilon$, which is a direct CP violation in $K ¥to ¥pi ¥pi$.
References:
arXiv:1707.06999, Phys.Rev.Lett. 119 (2017) 20, 201802
arXiv:1711.11030, JHEP 05 (2018) 024
arXiv:1712.04959, JHEP 04 (2018) 019
Takuya Furusawa, TITECH
[KEK-Keio-YITP-Joint seminar] Global anomaly matching in the higher-dimensional CP^N model
Online (Zoom)
“An ‘t Hooft anomaly is an obstruction to gauge global symmetries and constrains low-energy behaviors of a system. In this talk, we focus on the 3D CP^N model, an effective field theory of quantum anti-ferromagnets, and derive a mixed ‘t Hooft anomaly between the refection and magnetic symmetries. To detect the ‘t Hooft anomaly, we insert a flux for the reflection symmetry by putting the model on a non-orientable manifold. Then, we find an obstruction to gauge the magnetic symmetry. This anomaly indicates that even when the flavor symmetry is broken explicitly, the model doesn’t admit a unique gapped ground state as long as the refection and magnetic symmetries are respected. As an application, we also discuss the finite-temperature phase diagram of the CP^N model. This talk is based on: T.F., M. Hongo, “Global anomaly matching in the higher-dimensional $¥mathbb{CP}^{N?1}$ model”, PRB. 101, 155113, (2020).”
Ryosuke Sato, DESY
Axion fragmentation and its implication for relaxion scenario
Online (Zoom) https://kds.kek.jp/indico/event/34531/ The axion(-like particle) is ubiquitous in physics beyond the standard model. The axion has cosine-like potential, and the axion filed goes over a large number of wiggles if its initial velocity is large enough to overcome the barrier.
The axion(-like particle) is ubiquitous in physics beyond the standard model. The axion has cosine-like potential, and the axion filed goes over a large number of wiggles if its initial velocity is large enough to overcome the barrier.
During this process, the axion quantum fluctuation grows exponentially and this growth of quantum fluctuation gives friction to zeromode.
We denote this phenomenon as axion fragmentation, and discuss it in detail.
We also discuss its implication for the relaxion scenario which is a solution for the electroweak hierarchy problem.
Takahisa Igata, KEK
[cosmophys seminar] Polarization patterns on the outer edge of the black hole shadow and the gravitational Faraday rotation
Online (Zoom)
