# Seminar Report

## ABBL/iTHEMS Astro Seminar by Prof. Jin Matsumoto on December 10, 2021

2021-12-17

Prof. Jin Matsumoto (Assistant Professor, Keio Institute of Pure and Applied Sciences (KiPAS), Graduate School of Science and Technology, Keio University) gave a nice presentation on "Magnetic field dependence of neutrino-driven core-collapse supernova models". In the presentation, Prof. Matsumoto introduced his neutrino-radiation-hydrodynamics supernova code (3DnSNe, Takiwaki et al. 2016) to include magnetohydrodynamics (MHD). Using this code, he performed three-dimensional MHD simulations for the evolution of non-rotating stellar cores focusing on the difference in the magnetic field of the progenitors. He found that the neutrino-driven explosion occurs in both the weak and strong magnetic field models. It was concluded that the neutrino heating is the main driver for the explosion in his models, whereas the strong magnetic field slightly supports the explosion.

Reported by Shigehiro Nagataki

Magnetic field dependence of neutrino-driven core-collapse supernova models

December 10 at 14:00 - 15:00, 2021

# Seminar Report

## NEW WG Seminar by Dr. Yusuke Yamada on December 15, 2021

2021-12-22

Yusuke Yamada (RESCEU/Tokyo) gave a talk on "Cosmological particle production as Stokes phenomena." Particle production from the vacuum takes place in the presence of time-dependent backgrounds, and is of interest in various fields of physics. Yusuke reconsidered the particle production from a viewpoint of the Stokes phenomenon, a mathematical concept in theory of differential equations, and discussed its application to the early Universe. Yusuke pointed out that the Stokes-phenomenon viewpoint gives a systematic and powerful framework to investigate the realtime dynamics of the particle production. About 20 people have joined the seminar, and enjoyed active discussions during and even after the seminar.

Reported by Hidetoshi Taya

Cosmological particle production as Stokes phenomena

December 15 at 13:30 - 15:00, 2021

# Seminar Report

## iTHEMS Biology Seminar by Prof. Hidetoshi Shimodaira on December 16, 2021

2021-12-17

On December 16, Dr. Motomu Matsui (University of Tokyo) gave a lecture titled "Revisiting Standard Methods for Phylogenetic Tree Inference" at the iTHEMS Biology Seminar. He described the Graph Partitioning (GS) method, a new molecular phylogenetic analysis method based on graph theory and clustering, and explained its usefulness when used with real data. The GS method can reveal protein family relationships that cannot be clarified by conventional molecular phylogenetic analysis using maximum likelihood or distance methods. It was a very meaningful seminar for many participants. Thank you very much!

Reported by Yuki Yazaki

Revisiting Standard Methods for Phylogenetic Tree Inference

December 16 at 10:00 - 11:00, 2021

# Seminar Report

## NEW WG Seminar by Dr. Tomoki Ozawa on December 20, 2021

2021-12-22

Tomoki Ozawa (Tohoku/AIMR) gave a talk on "Quantum metric of topological and non-topological insulators in AMO and other systems." Quantum metric, or more generally quantum geometry, is attracting great interest recently in condensed-matter physics. Tomoki gave a pedagogical introduction to the concept of quantum metric as well as recent experimental progresses including the first detection of the quantum metric using a diamond NV center. Tomoki then explained his recent results on this topic, in particular, on relations among quantum metric, topology, and the Kähler geometry. More than 30 people have joined the seminar and enjoyed fruitful discussions.

Reported by Hidetoshi Taya

Quantum metric of topological and non-topological insulators in AMO and other systems

December 20 at 13:30 - 15:00, 2021

# Book

## Reading the World through the Window of Math

2021-12-21

Authors: Hiroyasu Miyazaki, Akinori Tanaka, Ryosuke Iritani and Nagisa Hiroshima

Editor: Tetsuo Hatsuda and Ryosuke Shibato

Language: Japanese

Release date: November 19, 2021

Exploring Prime Numbers, AI, Biology, and the Universe

Young researchers who use math to tackle a variety of research themes explain their research and their career choices with fresh sensitivity.

# Paper of the Week

## Week 4, December 2021

2021-12-23

Title: Analytic Bootstrap in 2D Boundary Conformal Field Theory: Towards Braneworld Holography

Author: Yuya Kusuki

arXiv: http://arxiv.org/abs/2112.10984v1

Title: Polychronic Tunneling: New Tunneling Processes Experiencing Euclidean and Lorentzian Evolution Simultaneously

Author: Naritaka Oshita, Yutaro Shoji, Masahide Yamaguchi

arXiv: http://arxiv.org/abs/2112.10736v1

Title: Vacuum decay in the Lorentzian path integral

Author: Takumi Hayashi, Kohei Kamada, Naritaka Oshita, Jun'ichi Yokoyama

arXiv: http://arxiv.org/abs/2112.09284v1

Title: H.E.S.S. follow-up observations of Binary Black Hole Coalescence events during the second and third Gravitational Waves observing runs of Advanced LIGO and Advanced Virgo

Author: H.E.S.S. Collaboration (Naomi Tsuji)

Journal Reference: ApJ, 923, 109 (2021)

doi: https://doi.org/10.3847/1538-4357/ac2e04

arXiv: http://arxiv.org/abs/2112.08307v1

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