Gauge-equivariant neural networks as preconditioners in lattice QCD

2023年4月6日(木) 13:30 - 15:00

Prof. Tilo Wettig (Professor, Universität Regensburg, Germany)

We demonstrate that a state-of-the-art multi-grid preconditioner can be learned efficiently by gauge-equivariant neural networks. We show that the models require minimal re-training on different gauge configurations of the same gauge ensemble and to a large extent remain efficient under modest modifications of ensemble parameters. We also demonstrate that important paradigms such as communication avoidance are straightforward to implement in this framework.

会場: コモンルーム (246-248号室) (メイン会場) / via Zoom

イベント公式言語: 英語

Organizational meeting

2023年4月6日(木) 16:00 - 17:00

カトゥリン・ボシゥメン (数理創造プログラム 副プログラムディレクター)

The purpose of the organizational meetings is to discuss various topics of interest to the members of iTHEMS in the field of Biology, but also to participants of the iTHEMS BIology Seminar, irrespective of their field. The primary objective of this meeting will be to discuss recruitment of JRAs, SPDRs, and female researchers from Biology into iTHEMS. I hope we can identify the main obstacles and consider together possible solutions. As usual, any additional topic can be brought up spontaneously by participants. Anyone with thoughts about iTHEMS Biology is welcome to join us, no matter their field.

会場: via Zoom

イベント公式言語: 英語

Starter Meeting FY 2023

2023年4月7日(金) 12:30 - 15:00

At the beginning of a new fiscal year, every member makes a short presentation regarding one's own research.

会場: via Zoom / コモンルーム (246-248号室)

イベント公式言語: 英語

Introduction to the Renormalization group method as a powerful reduction method of dynamics.

2023年4月10日(月) 10:30 - 12:00

国広 悌二 (京都大学 名誉教授)

Extracting effective slow dynamics with fewer degrees of freedom from a complex system with many degrees of freedom is of basic importance in all areas of Science. Typical examples include the derivation of the amplitude and phase dynamics from nonlinear oscillators, that of the Boltzmann equation from Hamilton dynamics, which is further reduced to fluid dynamics and so on. The purpose of this talk is to give an elementary introduction to the renormalization group (RG) method as a powerful reduction method of differential (difference) equations in terms of the notion of envelopes. Some simple examples will be worked out in this method, which include the van der Pol (Rayleigh) equation with its discrete analog and a generic system with a bifurcation. In the final part, we list up various examples to which the RG method has been successfully applied.

会場: セミナー室 (359号室) (メイン会場) / via Zoom

イベント公式言語: 英語

An overview on the nuclear equation of state studied from ground and collective excited state properties of nuclei

2023年4月12日(水) 13:30 - 15:00

Dr. Xavier Roca-Maza (Associate Professor, Department of Physics, University of Milan, Italy)

This contribution reviews a selection of available constraints to the nuclear equation of state (EoS) around saturation density from nuclear structure calculations on ground and collective excited state properties of atomic nuclei [1]. It concentrates on predictions based on self-consistent mean-field calculations, which can be considered as an approximate realization of an exact energy density functional (EDF). Mostly, EDFs are currently derived from effective interactions commonly fitted to nuclear masses, charge radii and, in many cases, also to pseudo-data such as nuclear matter properties. Although in a model dependent way, EDFs constitute nowadays a unique tool to reliablyand consistently access bulk ground state and collective excited state properties of atomic nuclei along the nuclear chart as well as the EoS. The impact on the EoS of the new CREx [2] and PREx [3] measurments of the parity violating asymmetry (ground state observable) in 48Ca and 208Pb, respectively, will be also discussed [4,5] and compared to previously presented results on collective excitations. As the main conclusion, the isospin dependence of the nuclear EoS around saturation density and, to a lesser extent, the nuclear matter incompressibility remain to be accurately determined. Experimental and theoretical efforts in finding and measuring observables specially sensitive to the EoS properties are of paramount importance, not only for low-energy nuclear physics but also for nuclear astrophysics applications.

会場: 理化学研究所 和光キャンパス RIBF棟 2階 大会議室 (メイン会場) / via Zoom

イベント公式言語: 英語

Emergence of Extreme Universe from Quantum Information

2023年4月17日(月) 16:00 - 17:30

高柳 匡 (京都大学 基礎物理学研究所 教授)

Recently, a new interpretation of gravitational spacetime in terms of quantum entanglement has been obtained. The idea of holography in string theory provides a simple geometric computation of entanglement entropy. This generalizes the well-known Bekenstein-Hawking formula of black hole entropy and strongly suggests that a gravitational spacetime consists of many qubits with quantum entanglement. Also a new progress on black hole information problem has been made recently by applying this idea. I will explain these developments in this colloquium.

会場: via Zoom

イベント公式言語: 英語

Towards EeV Neutrino Astronomy with GRAND

2023年4月18日(火) 14:00 - 15:15

クミコ・コテラ (Associate Professor, Institute of Astrophysics, France)

We are living exciting times: we are now able to probe the most violent events of the Universe with diverse messengers (cosmic rays, neutrinos, photons and gravitational waves). One challenge to complete the multi-messenger picture resides in the highest energies, as no ultra-high energy neutrinos have been observed yet. This challenge could be undertaken by the GRAND (Giant Radio Array for Neutrino Detection) project, which aims at detecting ultra-high energy particles, with a colossal array of 200'000 antennas over 200'000 km2, split into ~20 sub-arrays of ~10'000 km2 deployed worldwide. In this talk, we will present preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution.

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

X-ray study on the synchrotron emission in Kepler's SNR

2023年5月19日(金) 14:00 - 15:00

Dr. Vincenzo Sapienza (東京大学 大学院理学系研究科 物理学専攻 博士課程)

Synchrotron X-ray emission in young supernova remnants (SNRs) is a powerful diagnostic tool to study the population of high energy electrons accelerated at the shock front. We performed a spatially resolved spectral analysis of the young Kepler's SNR, where we identify two different regimes of particle acceleration. In the north, where the shock interacts with a dense circumstellar medium (CSM), we found a more efficient acceleration than in the south, where the shock velocity is higher and there are no signs of shock interaction with dense CSM. We also studied the temporal evolution of the synchrotron flux, from 2006 to 2014. A number of regions show a steady synchrotron flux and equal cooling and acceleration times. However, we found some regions where we measured a significant decrease in flux from 2006 to 2014. Our results display a coherent picture of the different regimes of electron acceleration observed in Kepler's SNR. Also If I will have time during the seminar it will be nice to present also some preliminary results I will have in the SN 1987A project.

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

Spectral correlations and scrambling dynamics in Sachdev-Ye-Kitaev type models

2023年5月30日(火) 13:30 - 15:00

手塚 真樹 (京都大学 大学院理学研究科 物理学・宇宙物理学専攻 助教)

Note: Due to unexpected trouble, we have made the decision to postpone the seminar scheduled for February 21 to May 30. Sorry for the trouble. Abstract: The Sachdev-Ye-Kitaev (SYK) model, proposed in 2015, is a quantum mechanical model of N Majorana or complex fermions with all-to-all random four-body interactions. The model has attracted significant attention over the years due to its features such as the existence of the large-N solution with maximally chaotic behavior at low temperatures and holographic correspondence to low-dimensional gravity. The sparse version of the SYK model reproduces essential features of the original model for reduced numbers of disorder parameters. We recently proposed [1] a further simplification, where we set the nonzero couplings to be +1 or -1 rather than sampling from a continuous distribution such as Gaussian. This binary-coupling model exhibits strong correlations in the spectrum, as observed in the spectral form factor, more efficiently in terms of the number of nonzero terms than in the Gaussian distribution case. We also discuss the scrambling dynamics with the binary-coupling sparse SYK model, comparing the model with the original model as well as the SYK model with random two-body terms [2], where the localization of the many-body eigenstates in the Fock space has been quantitatively studied [3,4].

会場: コモンルーム (246-248号室) / via Zoom

イベント公式言語: 英語

g-RIPS-Sendai 2023

2023年6月19日(月) - 8月8日(火)

東北大学材料科学高等研究所（AIMR）では、2018年よりg-RIPS (Graduate-level Research in Industrial Projects for Students)-Sendai プログラムを開催しています。本プログラムはパートナー企業から提供された課題に、アメリカと国内からの参加者がグループとなって集中的に取り組み、解決に至る道筋を学ぶ国際インターンシッププログラムのひとつです。本年のg-RIPS-Sendai 2023の詳細は、関連リンクより本プログラムのウェブサイトをご覧ください。 主催: 東北大学・数理科学連携研究センター (RACMaS) 東北大学・知の創出センター (TFC) 東北大学・材料科学高等研究所 (AIMR) 共催: 理化学研究所・数理創造プログラム (iTHEMS) Institute for Pure & Applied Mathematics, UCLA

会場: 東北大学 片平キャンパス 材料科学高等研究所（AIMR）

6th Workshop on Virus Dynamics

2023年7月4日(火) - 6日(木)

カトゥリン・ボシゥメン (数理創造プログラム 副プログラムディレクター)
岩見 真吾 (名古屋大学 大学院理学研究科 教授)

The Workshop on Virus Dynamics is an international meeting held every 2 years. It brings virologists, immunologists, and microbiologists together with mathematical and computational modellers, bioinformaticians, bioengineers, virophysicists, and systems biologists to discuss current approaches and challenges in modelling and analyzing different aspects of virus and immune system dynamics, and associated vaccines and therapeutics. This 6th version of the workshop builds on the success of previous ones held in Frankfurt (2013), Toronto (2015), Heidelberg (2017), Paris (2019) and virtually (2021). It is supported by the Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) program at RIKEN, by Nagoya University, and by the Japan Science and Technology Agency. Up-to-date information and registration is available via the website. The workshop is for in-person participation only (no virtual or hybrid option).

会場: 名古屋大学 野依記念学術交流館 東山キャンパス

イベント公式言語: 英語