iTHEMS Weekly News Letter

Seminar Report

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


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

Seminar Report

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


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

Seminar Report

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


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

Seminar Report

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


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


Reading the World through the Window of Math thumbnail

Reading the World through the Window of Math


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


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

Title: Polychronic Tunneling: New Tunneling Processes Experiencing Euclidean and Lorentzian Evolution Simultaneously
Author: Naritaka Oshita, Yutaro Shoji, Masahide Yamaguchi

Title: Vacuum decay in the Lorentzian path integral
Author: Takumi Hayashi, Kohei Kamada, Naritaka Oshita, Jun'ichi Yokoyama

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)

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