# ニュース

12 news in 2022

2022-01-25

セミナーレポート

## NEW WG Seminar by Mr. Tomohiro Tanogami on January 20, 2022

Tomohiro Tanogami from Kyoto University gave a talk titled "A simple XY model for cascade transfer." Cascade transfer is a ubiquitous phenomenon that appears in various physical systems. During a cascade transfer an inviscid conserved quantity such as energy is transferred conservatively from large/small to small/large scales, which results in a universal scaling law in the spectrum (e.g., Kolmogorov energy spectrum). In the talk, Tomohiro proposed a simple XY model which shows inverse energy cascade with a non-Kolmogorov energy spectrum and pointed out that the model may characterize a novel "universality class" of cascade transfer. Tomohiro also explained possible relations between his model and, e.g., spin and atmospheric turbulences. About 20 physicists have joined the seminar and enjoyed discussions from various viewpoints. Reported by Hidetoshi Taya

2022-01-24

プレスリリース

2022-01-20

イベントスケジュール

## Events for the 5th week of January 2022

Thursday, January 27, 10:00– 11:00 iTHEMS Biology Seminar Friday, January 28, 12:30- Coffee Meeting Saturday, January 29, 15:30- 16:40 RIKEN AIP-Suri-joshi Joint Seminar

2022-01-20

セミナーレポート

## iTHEMS Biology Seminar by Dr. Hiroyasu Miyazaki on January 20, 2022

In the iTHEMS Biology Seminar on 20th January, Dr. Hiroyasu Miyazaki (RIKEN iTHEMS) gave a talk on the topological aspect of chemical reaction network. His talk is composed of two parts: motivation and result part and method part. In the first part, he mentioned the reduction of the chemical reaction network in E. Coli and its result which shows the same steady state as that before the reduction. In the second part, he explained how the network should be reduced. The topological information of the network can be described by using the matrix and the vector. He explained that the quotient network is defined to have a sequence of linear maps called “exact sequence”, which describes the relation among the original network, the subnetwork and the quotient network. We enjoyed his beautiful talk. From the audiences, the lively discussion arose during and after the talk. Thank you very much, Hiroyasu! Reported by Hiroshi Yokota

2022-01-20

## Week 4, January 2022

Title: Current-induced inverse symmetry breaking and asymmetric critical phenomena at current-driven tricritical point Author: Masataka Matsumoto, Shin Nakamura arXiv: http://arxiv.org/abs/2201.06894v1 Title: Global study of the scalar quasi-normal modes of Kerr-AdS${}_5$ black holes: Stability, thermality, and horizon area quantization Author: Issei Koga, Naritaka Oshita, Kazushige Ueda arXiv: http://arxiv.org/abs/2201.07267v1

2022-01-18

セミナーレポート

## DMWG Seinar by Dr. Kanji Mori on January 17, 2022

In this era of multi-messenger astronomy, axion-like particle (ALP) searches using astrophysical transients are now excitingly discussed. ALPs are an extended class of particles from QCD axion, which could solve the strong CP problem of the Standard Model, and dark matter (DM) candidates of various connections to the physics beyond the Standard Model. ALPs could interact with our sector through their coupling to the photon, electron, and/or nucleons. The coupling of ALP to the photon is previously investigated using observations of SN 1987A, the most famous supernova explosion. MeV gamma-ray signals are expected when considering the conversion of ALP outside the stellar envelope, hence no observations of the associated gamma-ray emission to the supernova lead to the constraint on the coupling strength, for example. Also, the existence of such coupling should modify the dynamics of supernovae. When a star explodes, the difference between the masses of the progenitor star and the resulting compact object sources the radiation, neutrino emission, and kinetic energy of the ejecta material. ALP could be an additional channel for the energy release while its absorption heats the supernova. The balance between heating and cooling controls the supernova dynamics and shock restoration, which directly relates to the electromagnetic observables. Dr. Mori has shown that the heating rate is very sensitive to the coupling strength and enhancement of the electromagnetic emission is expected in the pre-supernova stage. The signatures could also be visible in the neutrino sector after the explosion. The results are fantastic, and there are a lot of things to do. For example, the inclusion of the ALP-nucleon coupling effects is an interesting direction to pursue. Updates in the understanding of stellar models are important as well. We should see the signature of ALP in the near future in this field! Reported by Nagisa Hiroshima

2022-01-17

セミナーレポート

## iTHEMS Biology Seminar by Dr. Wataru Nishima on January 13, 2022

Dr. Wataru Nishima (New Mexico Consortium, USA) gave a very interesting presentation about his published paper on the spike protein of the SARS-CoV-2, the virus which causes COVID-19 [1]. He　described the conformational change which the SARS-CoV-2 spike protein undergoes when it fuses with the host cell to initiate infection. His work offers and interesting alternative view of the process wherein parts of the spike　protein ends up inside the host cell. This differs from the usual view where the spike protein would be left on the outside of the cell after virus fusion with the host. This alternative hypothesis could have important implication for better understanding disease severity, e.g. based on the possible toxic effect of spike protein components shed as part of the fusion process. Dr. Nishima's expertise is primarily in Molecular Dynamics and Bioinformatics and he is very interested to establish new collaborations with iTHEMS members. Reported by Catherine Beauchemin

2022-01-17

ホットトピック

## 「数理の窓から世界を読みとく」若手研究者たちの感性に注目

「数理の窓から世界を読みとく」についてのコラム記事がイマジニア社のテンミニッツTVに掲載されました。 iTHEMSの若手研究者たちが執筆陣を担った共著「数理の窓から世界を読みとく: 素数・AI.生物・宇宙をつなぐ」 (初田哲男・柴藤亮介編著、岩波書店)をもとに数理の魅力が紹介されています。 詳細は関連リンクをご覧下さい。

2022-01-14

リサーチニュース

## RIKEN NEWS: ゲノム情報に隠された進化の法則を探る

ジェフリ・フォーセット上級研究員のインタビュー記事が、理研の研究紹介ページ「クローズアップ科学道 2022」に掲載されました。 地球上に生命が誕生して約40憶年。長い年月を経て生物は多種多様に進化してきました。これはゲノムの進化の歴史でもあります。種ごとの違いはどのようにして生じてきたのか、ジェフリ・フォーセット上級研究員（以下、研究員）は、数理科学のアプローチを取り入れながらこの謎の解明に挑戦しています。 続きは、関連リンクをご覧ください。

2022-01-13

## Week 3, January 2022

Title: Biexciton-like quartet condensates in an electron-hole liquid Author: Yixin Guo, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2201.03031v1 Title: Optimized Two-Baryon Operators in Lattice QCD Author: Yan Lyu, Hui Tong, Takuya Sugiura, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Jie Meng, Takaya Miyamoto arXiv: http://arxiv.org/abs/2201.02782v1 Title: A MeerKAT, e-MERLIN, H.E.S.S. and Swift search for persistent and transient emission associated with three localised FRBs Author: James O. Chibueze, et al.; H.E.S.S. Collaboration (Naomi Tsuji) arXiv: http://arxiv.org/abs/2201.00069v1 Title: Analyticity of the energy in an Ising spin glass with correlated disorder Author: Hidetoshi Nishimori Journal Reference: J. Phys. A 55, 045001 (2022) doi: https://doi.org/10.1088/1751-8121/ac44ef arXiv: http://arxiv.org/abs/2110.01196v2 Title: The hyperon spectrum from lattice QCD Author: Nolan Miller, Grant Bradley, M. A. Clark, Ben Hörz, Dean Howarth, Malcolm Lazarow, Henry Monge-Camacho, Amy Nicholson, Enrico Rinaldi, Pavlos Vranas, André Walker-Loud arXiv: http://arxiv.org/abs/2201.01343v1 Title: A path integral derivation of the equations of anomalous Hall effect Author: Kazuo Fujikawa, Koichiro Umetsu arXiv: http://arxiv.org/abs/2201.01104v1 Title: Gravitational wave asteroseismology on cooling neutron stars Author: Hajime Sotani, Akira Dohi arXiv: http://arxiv.org/abs/2201.00648v1 Title: Non-Equilibrating a Black Hole with Inhomogeneous Quantum Quench Author: Kanato Goto, Masahiro Nozaki, Kotaro Tamaoka, Mao Tian Tan, Shinsei Ryu arXiv: http://arxiv.org/abs/2112.14388v1 Title: Chaos by Magic Author: Kanato Goto, Tomoki Nosaka, Masahiro Nozaki arXiv: http://arxiv.org/abs/2112.14593v1 Title: Cooling of Isolated Neutron Stars with Pion Condensation: Possible Fast Cooling in a Low-Symmetry-Energy Model Author: Akira Dohi, Helei Liu, Tsuneo Noda, Masa-aki Hashimoto arXiv: http://arxiv.org/abs/2112.13302v1 Title: Dynamical stability and filamentary instability in holographic conductors Author: Shuta Ishigaki, Shunichiro Kinoshita, Masataka Matsumoto arXiv: http://arxiv.org/abs/2112.11677v2

2022-01-13

イベントスケジュール

## Events for the 4th week of January 2022

Monday, January 17, 11:00– 12:00 DMWG Seminar Thursday, January 20, 10:00– 11:00 iTHEMS Biology Seminar Thursday, January 20, 13:30– 15:00 NEW WG Seminar Friday, January 21, 12:30- Coffee Meeting

2022-01-12

セミナーレポート

## iTHEMS Biology Seminar by Prof. Tetsuya Yamamoto on January 6, 2022

On January 6th, Prof. Tetsuya Yamamoto gave us a comprehensive talk about the physical aspects of nuclear bodies. He first introduced the liquid-liquid phase separation and other self-assembly mechanisms in soft-matter physics, such as micelle formation, with motivations from the experimental side. In the main part, he told us about three recent topics regarding how RNAs' dynamics and sequence properties lead to different types of assembly of nuclear bodies. The mathematical formulation, schematic figures, and comparisons with experiments were clear to understand. We are very grateful to Prof. Yamamoto for the exciting seminar. Reported by Kyosuke Adachi

12 news in 2022