セミナー 2018年

Yasunori Lee, Kavli IPMU

A study of time-reversal symmetry of Abelian anyons

Meeting room 3, Kenkyu honkan 1F, slides (kek.jp only)
(2+1)d TQFTs have been studied from various points of view. Recently, the actions of discrete symmetries on them are attracting attention in the context of topological phases of matter. In this talk, I will first review the basic concepts and formalism, and then present the analysis of time-reversal symmetries on Abelian anyon systems mainly focusing on their anomaly.

Takeshi Morita, Shizuoka University

Quantum quench of one-dimensional Fermi gas and thermalization to generalized Gibbs ensembles

Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
Understanding thermalization and entropy production is one of the outstanding problem in theoretical physics. However, in integrable systems, we can explicitly solve the time evolution and observe thermalization to so called generalized Gibbs ensembles. In this talk, we demonstrate it in one-dimensional free Fermi gas, which are trapped in external potentials or a circle, through quantum quenches. We analytically compute local observables such as particle density and show that they always exhibit power law relaxation at late times. We find a simple rule which determines the power law exponent. Our findings are, in principle, observable in experiments in an one dimensional free Fermi gas or Tonk’s gas (Bose gas with infinite repulsion).

Keiichi Maeda, Kyoto University

Constraining progenitors and explosion mechanisms of supernovae through their nucleosynthesis characteristics

Meeting room 3, Kenkyu honkan 1F, slides (kek.jp only)
Supernovae (SNe) are the explosive death of stars, either triggered by gravitational collapse of massive stars (CCSNe; core-collapse SNe) or thermonuclear runway of a white dwarf (SNe Ia). Identifying the natures of their progenitors and explosion mechanisms is one of the central issues in stellar astrophysics and observational transient science. In this talk, I will first introduce basic concepts of the SN explosion nucleosynthesis. Then, a review is given on how different progenitors and explosion mechanisms would manifest themselves in observational properties of SNe. Finally, I will quickly go through some examples of recent progresses in individual topics, where the observational data are used to constraint the natures of the progenitors and explosions through the nucleosynthesis arguments; (1) the white dwarf masses and modes of thermonuclear runaway in SNe Ia, (2) the masses of progenitor stars for different classes of CCSNe, and (3) the standard neutrino-driven explosion models and beyond as confronted by the observations of CCSNe and peculiar outliers (such as those associated with Gamma-Ray Bursts).

Tim Maudlin, New York University

What is Wavefunction Realism?

Seminar room, Kenkyu honkan 3F
In the foundations of physics literature, the question is sometimes raised about whether one should—or even can—be a realist about the wavefunction. This query offers two targets for analysis and explication: “realist” and “wavefunction”. The first term is used in many different ways, as is the second, and to get down to a non-trivial and sensible question one has to specify exactly what one has in mind. I will argue that given the only sensible and non-trivial way to make a clear question here, the indeed one ought to be a “realist” about the “wavefunction”. There never should have been much controversy here, and the recent theorem by Pusey, Barrett and Rudolph settles the issue.

Anupam Mazumdar, University of Groningen

Scale free theory of infinite derivative gravity in the ultraviolet

Seminar room, Kenkyu honkan 3F
I will discuss how infinite derivative theory of gravity can be made ghost free and scale free in the ultraviolet to resolve blackhole and cosmological singularities in 4 spacetime dimensions. I will also discuss the consequences for infinite derivative gravity in 3 spacetime dimensions in AdS.

井元信之, 大阪大学


Seminar room, Kenkyu honkan 3F

Sergei V. Ketov, Tokyo Metropolitan University and Kavli IPMU

New supergravity framework and its applications to the early Universe cosmology

Meeting room 1, Kenkyu honkan 1F, slides (kek.jp only)
in the first part of my talk I give a very simple introduction to the Dark Side of the Universe (cosmological inflation, dark energy and dark matter), and then briefly review its possible gravitational origin. In the second part of my talk I introduce the supergravity description of the Dark Universe and describe the new tools in the supergravity model building.

Keisuke Harigaya, Institute for Advanced Study

Higgs parity, strong CP problem and unification

Seminar room, Kenkyu honkan 3F
The quartic coupling of the Standard Model Higgs nearly vanishes at a high energy scale. We show that this is explained by the parity symmetry and its spontaneous break down by the condensation of the parity partner of the Higgs. The parity can solve the strong CP problem. The theory is embedded into SO(10) unification and the precise gauge coupling unification is achieved.

山下雅樹, ICRR


暗黒物質は銀河団の運動からF. Zwickyにより80年前からその存在を示唆されてきた。その後、銀河の回転速度、宇宙背景放射などの観測により、その存在は確実視されている。一方、素粒子模型からも期待される暗黒物質であるが、未だにその正体は不明である。宇宙の物質の約80%を担っている暗黒物質は我々の身の周りにも飛来し、1Lに数個程度存在していると考えられ、直接探索ではこの粒子の検出を目指している。本講演では地下実験室における液体キセノンを中心とした暗黒物質直接探索実験を紹介する。

Di-Lun Yang, Yukawa Institute of Theoretical Physics, Kyoto University

Chiral kinetic theory and quantum transport of chiral fluids

Seminar room, Kenkyu honkan 3F, slides (kek.jp only)
Recently, the anomalous transport of Weyl fermions such as the renowned chiral magnetic effect stemming from the chiral anomaly has been widely studied in relativistic heavy ion collisions, Weyl semimetals, or even in astrophysics. Although such anomalous transport is in general non-dissipative and independent of couplings in thermal equilibrium, the non-equilibrium (or near-equilibrium) transport of Weyl fermions could be affected by other quantum effects and interactions. The chiral kinetic theory (CKT), which delineates quasi-particle transport with the chiral anomaly, is a useful tool to investigate quantum transport in and out of equilibrium for Weyl-fermion systems at weak coupling. In this talk, I will review the recent development of CKT based on quantum field theories, which manifests Lorentz covariance and consistently incorporates collisions. We then apply the CKT to study second-order quantum transport of chiral fluids near local equilibrium. By using a relaxation-time approximation, novel anomalous Hall currents pertinent to interactions and triggered by electric fields and temperature/chemical-potential gradients are discovered. Moreover, the chiral magnetic/vortical effects receive viscous corrections. In addition, one finds that the CKT yields a non-vanishing antisymmetric component of the canonical energy-momentum tensor in chiral fluids with vorticity, which reveals the spin-orbit interaction responsible for angular-momentum transfer in the presence of an axial chemical potential.
References :
Di-Lun Yang, arXiv:1807.02395
Yoshimasa Hidaka, Di-Lun Yang, Phys.Rev. D98 (2018) no.1, 016012, arXiv:1801.08253
Yoshimasa Hidaka, Shi Pu, Di-Lun Yang , Phys. Rev. D 97 (2018) no.1, 016004, arXiv:1710.00278
Yoshimasa Hidaka, Shi Pu, Di-Lun Yang , Phys.Rev. D95 (2017) no.9, 091901, (Rapid Communication), arXiv:1612.04630
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