The Functional Renormalisation Group: From the physics of strongly correlated systems to generative models

2025年12月5日(金) 10:30 - 12:00

Jan Martin Pawlowski (Professor, Institute for Theoretical Physics, University of Heidelberg, Germany)

In the past decades, the functional renormalisation group (fRG) has matured into a comprehensive approach to strongly-correlated (non-perturbative) systems, covering quantitatively both universal and non-universal phenomena. The fRG also constitutes an ideal approach for unravelling structural aspects of quantum field theories. This is not only interesting for studies in mathematical physics, but also guides systematic diagrammatic expansion schemes. It is also used to set up novel statistical (lattice) approaches to non-perturbative phenomena. In the present talk I survey these advances and illustrate the progress with selected examples ranging from ultracold atoms, QCD and quantum gravity to novel generative architectures for lattice simulations and beyond.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Quantum Information in Scattering: From Amplitude Poles to Entanglement Features

2025年12月4日(木) 14:00 - 16:00

蘇 俊文 (Postdoctoral Researcher, Department of Physics, Tsinghua University, Beijing, China)

Probing quantum entanglement in high-energy collisions has recently become a rapidly growing direction in particle physics, aiming to measure quantum correlations at the highest energy scales accessible to humans. A key question is how such entanglement relies on the analytic structure of scattering amplitudes. In this talk, I will show that the pole structure, associated with intermediate heavy particles, leads to distinctive entanglement features. When a heavy particle mediates inelastic scatterings with three or more final particles, the entanglement entropy between its decay products and the rest exhibits a universal dip as the energy increases, reflecting the limited information flow through on-shell heavy particles and signaling entanglement suppression in the heavy-particle-dominated regime. This reveals entanglement structures beyond the usual “area-law” behavior of 2-to-2 processes. Finally, I will comment on possible ways to probe these features experimentally through analyses of final-state phase-space distributions. This talk is based on JHEP 10 (2025) 003 [arXiv: 2507.03555].

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

Biological Background of Duplicated Sequence Evolution: A Focus on Gene Conversion

2025年12月4日(木) 13:00 - 14:00

大窪 健児 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 基礎科学特別研究員)

Duplicated sequences—such as gene families, tandem arrays, and segmental duplications—are common in many genomes. Their evolution is shaped by several biological processes, including mutation, recombination, duplication, deletion, and gene conversion. Among these, gene conversion is especially important because it can make nearby copies more similar, while leaving distant copies free to diverge. In this seminar, I will give a broad and accessible overview of the biological background related to duplicated sequences, with a particular focus on what is known about gene conversion. I will summarize well-established patterns such as its dependence on genomic distance, sequence similarity, and recombination context. These biological features are often studied separately, so organizing them in one place can help provide a clearer foundation. The goal of the talk is to outline the biological principles that motivate thinking about duplicated sequences in a more formal or quantitative way in the future. I will not discuss specific model details. Instead, this presentation will serve as background preparation for later theoretical work.

会場: via Zoom / セミナー室 (359号室)

イベント公式言語: 英語

Spectral Network and Betti Lagrangians

2025年12月3日(水) 14:00 - 16:00

Yoonjae Nho (General Welfare Assistant, Seongdong District Office, Republic of Korea)

In this talk I will discuss the interface of spectral network theory and real contact and symplectic topology. For the first hour, I will give an introduction to spectral network theory using the Berk-Nevins-Roberts example, and review symplectic topology. For the second hour, I will talk about how GMN (Gaiotto-Moore-Neitzke) network theory can be interpreted from a symplectic perspective. I will then give an introduction to weave theory, which allows one to construct certain Lagrangian generalizations of spectral curves. I will then explain how to combinatorially compute spectral networks, with some applications. This is based on joint work with Roger Casals [1].

会場: via Zoom (メイン会場) / セミナー室 (359号室)

イベント公式言語: 英語

Quantum Computing Journal Club #1

2025年12月2日(火) 10:00 - 12:00

Bring a recent paper on quantum computing for discussion. No need to prepare slides.

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

第30回 MACSコロキウム

2025年11月28日(金) 14:45 - 18:00

石川 勲 (京都大学 大学院理学研究科 附属サイエンス連携探索センター (SACRA) 特定准教授)
黒谷 賢一 (京都大学 大学院理学研究科 附属サイエンス連携探索センター (SACRA) 准教授)

14:45-15:00 ティータイムディスカッション 15:00-16:00 石川 勲（京都大学大学院理学研究科 附属サイエンス連携探索センター 特定准教授）「関数空間で読み解く力学系のデータ駆動解析」 16:15-17:15 黒谷 賢一（京都大学大学院理学研究科 附属サイエンス連携探索センター 准教授）「植物科学とデータ科学の融合」 17:15-18:00 継続討論会

会場: 京都大学 理学研究科セミナーハウス（建物配置図（北部構内）【10】の建物）

イベント公式言語: 日本語

From phase reduction to hypergraphs: the higher-order dynamics of coupled phase oscillators

2025年11月27日(木) 13:00 - 14:00

リッカルド・ムオロ (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 基礎科学特別研究員)

Networks are powerful tools in the modeling of complex systems, but they do not always capture the right interactions when multiple units are involved simultaneously. Such many-body interactions are encoded by higher-order structures which can be thought as extensions of networks. Over the last years, higher-order networks have been the focus of great excitement, since this novel framework has enormous potential for applications. In this talk, I will give an overview of higher-order interactions and their effects on nonlinear dynamics. I will introduce the basics of dynamics on networks and its extension to the case of higher-order interactions. As examples of the effects on nonlinear dynamics, I will discuss the case of phase reduction for systems with higher-order interactions and show the effects on synchronization dynamics.

会場: セミナー室 (359号室) / via Zoom

イベント公式言語: 英語

Introduction to Game Theory #3

2025年11月27日(木) 11:00 - 12:00

村瀬 洋介 (理化学研究所 数理創造研究センター (iTHEMS) 数理展開部門 数理社会科学チーム チームディレクター)

An introductory lecture on game theory to promote potential interdisciplinary collaborations. No prior knowledge is required — the lecture is intended for non-experts. We will cover the fundamental concepts to help you build an intuitive understanding of how game theory analyzes strategic interactions. After briefly reviewing the previous lectures, we will talk about repeated games, where players are engaged in games repeatedly.

会場: via Zoom (メイン会場) / セミナー室 (359号室)

イベント公式言語: 英語

Hamiltonian Learning and Dynamics Prediction via Machine Learning

2025年11月26日(水) 15:00 - 16:00

李 可仁 (Assistant Professor, College of Physics and Optoelectronic Engineering, Shenzhen University, China)

Accurate prediction of quantum Hamiltonian dynamics and identification of Hamiltonian parameters are crucial for advancements in quantum simulations, error correction, and control protocols. This talk introduces a machine learning model with dual capabilities: it can deduce time-dependent Hamiltonian parameters from observed changes in local observables within quantum many-body systems, and it can predict the evolution of these observables based on Hamiltonian parameters. The model’s validity was confirmed through theoretical simulations across various scenarios and further validated by two experiments. Initially, the model was applied to a Nuclear Magnetic Resonance quantum computer, where it accurately predicted the dynamics of local observables. The model was then tested on a superconducting quantum computer with initially unknown Hamiltonian parameters, successfully inferring them. We believe that machine learning techniques hold great promise for enhancing a wide range of quantum computing tasks, including parameter estimation, noise characterization, feedback control, and quantum control optimization.

会場: via Zoom

イベント公式言語: 英語

Adaptive navigation strategies in adversarial predator-prey contexts

2025年11月20日(木) 13:00 - 14:00

西海 望 (新潟大学 教育研究院 自然科学系 特任准教授)

Animal navigation has long been a central topic in behavioral biology. In predator-prey systems, both predators and prey must navigate strategically - predators to capture prey and prey to reach safety - each evolving to outsmart the other through coevolution. To uncover the essence of these navigation strategies, I have investigated behavioral mechanisms across taxa. In bats, my collaborators and I found that they integrate multiple sensory and flight tactics to keep erratically flying moths within detection range. In pigeons, we discovered that individuals anticipating drone attacks adjust their positions toward the rear within the flock. I will also introduce an experimental framework that enables controlled interactions between real animals and virtual agents driven by reactive motion control, allowing quantitative tests of navigation efficiency. Through this seminar, I aim to highlight how studies of predator-prey navigation can bridge biology and engineering, providing insights into adaptive decision-making in dynamic environments.

会場: セミナー室 (359号室) / via Zoom

イベント公式言語: 英語

9th QGG Intensive Lectures – Correlation Effects in Quantum Many-Body Systems: Some Prototypical Examples in Condensed Matter Physics

2025年11月19日(水) - 20日(木)

川上 則雄 (理化学研究所 最先端研究プラットフォーム連携 (TRIP) 事業本部 基礎量子科学研究プログラム 副プログラムディレクター)

The ninth installment of the Intensive Lecture Series, organized by the Quantum Gravity Gatherings (QGG) study group at RIKEN iTHEMS, will feature Prof. Norio Kawakami from the Fundamental Quantum Science Program (FQSP) under RIKEN's Transformative Research Innovative Platform (TRIP). Over the course of two days, Prof. Kawakami will deliver a lecture series on quantum many-body systems. In recent years, insights from quantum many-body physics have become central to research in quantum gravity, where correlation effects induced by gravity play nontrivial roles. By bridging perspectives from gravitational physics and quantum many-body dynamics, one hopes to understand how macroscopic spacetime and its geometric properties emerge from the collective behavior of quantum constituents at microscopic scales. In this lecture series, Prof. Kawakami will introduce the fundamental properties of correlation effects through representative examples in condensed matter physics. A distinctive aspect of this event is its joint organization with the Fundamental Quantum Science Program (FQSP) at RIKEN. The goal is to further strengthen connections between the quantum gravity, condensed matter, and quantum information communities. The lectures will be delivered in a blackboard-style format (in English), designed to foster interaction, active participation, and in-depth Q&A discussions. In addition, short talk sessions will be held, giving participants the opportunity to present briefly on topics of their choice. Through this informal and dynamic setting, we hope to spark active interactions among participants and create an environment where ideas can be shared openly and enthusiastically. Abstract: Some examples of theoretical methods to treat strongly correlated systems in condensed matter physics are explained. We start with the Kondo effect, which is one of the most fundamental quantum many-body problems and has been intensively studied to date in a wide variety of topics such as dilute magnetic alloys, heavy fermion systems, quantum dot systems, etc. Dynamical mean-field theory (DMFT) is then introduced, which enables us to systematically treat strongly correlated materials such as a Mott insulator. It is shown that the essence of DMFT is closely related to the Kondo effect. Furthermore, we explain how to apply conformal field theory (CFT) to treat correlation effects in one-dimensional electron systems.

会場: 研究本館 4階 435-437号室

イベント公式言語: 英語

Chiral anomaly in Hamiltonian lattice gauge theory

2025年11月18日(火) 10:00 - 12:00

山本 新 (理化学研究所 数理創造研究センター (iTHEMS) 数理展開部門 量子数理科学チーム 上級研究員)

The 4th quantum computing gathering organized by Quantum Computing Study Group

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

Mathematical Application Research Team Meeting #10

2025年11月14日(金) 16:00 - 17:00

緒方 芳子 (京都大学 数理解析研究所 (RIMS) 教授)

Mathematical Application Research Team invites Prof. Yoshiko Ogata from RIMS for this meeting. Her talk title will be announced later. You are welcome to join the meeting. The title and the abstract of her talk are: Title: Mixed state topological order: operator algebraic approach Abstract: We consider anyons in mixed states of two-dimensional quantum spin systems within the operator-algebraic framework of quantum statistical mechanics. To each state satisfying a mixed-state version of approximate Haag duality, we associate a braided C*-tensor category, which we interpret as describing the anyonic excitations of the state. We then investigate how these anyonic structures behave under interactions with the environment.

会場: セミナー室 (359号室) 3階 359号室 (メイン会場) / via Zoom

イベント公式言語: 英語

Contribution of star-forming galaxies to the cosmic gamma-ray background

2025年11月14日(金) 14:00 - 15:15

Junling Chen (東京大学 大学院数理科学研究科 博士課程)

Fermi Gamma-Ray Space Telescope has measured the diffuse extragalactic gamma-ray background (EGB) radiation in the energy range of 100 MeV to 820 GeV. Several candidate γ -ray sources have been proposed as the candidate components of the unresolved EGB, including active galactic nuclei (AGNs), millisecond pulsars, dark matter annihilation, and star-forming galaxies (SFGs), but their quantitative contribution has not yet been precisely determined. In this talk, I will introduce our latest physical model describing the gamma-ray emission mechanism from SFGs, and our estimate of the contribution of SFGs based on careful calibration with gamma-ray luminosities of nearby galaxies and physical quantities (star formation rate, stellar mass, and size) of galaxies observed by high-redshift galaxy surveys.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

数理科学のアウトリーチについての研究会 2025

2025年11月14日(金) - 16日(日)

今年の「数理科学のアウトリーチについての研究会」を、令和４年度ー８年度　文部科学省・科研費・学術変革領域 (A)「データ記述科学の創出と諸分野への横断的展開」のご援助のもとで、11月14日（金）12:30 ～16日（日）15:00 に「データ記述科学と数理科学のアウトリーチについての研究会」として、九州大学マス・フォア・インダストリ研究所で、対面とズームを併用して開催いたします。RIKEN iTHEMS（SUURI-COOL Kyushu）はこれを共催しています。

会場: 九州大学 伊都キャンパス IMI オーディトリアム W1-D-413 (メイン会場) / via Zoom

イベント公式言語: 日本語

The Uchuu simulations data set: large-scale structures and galaxies - Tomoaki Ishiyama

2025年11月13日(木) 14:00 - 15:30

石山 智明 (千葉大学 情報戦略機構 准教授)

I will introduce the Uchuu suite of large high-resolution cosmological N-body simulations. The largest simulation, named Uchuu, consists of 2.1 trillion dark matter particles in a box of side-length 2.0 Gpc/h, with particle mass of 3.27e8 Msun/h. The highest resolution simulation, Shin-Uchuu, consists of 262 billion particles in a box of side-length 140 Mpc/h, with particle mass of 8.97e5 Msun/h. Combining these simulations, we can follow the evolution of dark matter haloes and subhaloes spanning those hosting dwarf galaxies to massive galaxy clusters across an unprecedented volume from very high-z. We release N-body data (halo/subhalo catalogs and merger trees) and mock galaxy/AGN catalogs constructed using various models, which cover objects from z=0 to very high-z. These catalogs open a new window on understanding the large-scale structures and galaxy formation. In this presentation, I will also introduce results of cosmological simulations adopting a time-varying dark energy, conducted on the supercomputer Fugaku.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

DA Seminar: Machine learning for precipitation estimation and forecasting / Analysis of a Long-Lived Supercell: Life Cycle and Severe Weather Patterns in Northern Buenos Aires Province

2025年11月13日(木) 10:30 - 12:00

フアン・ルイス (理化学研究所 数理創造研究センター (iTHEMS) 数理展開部門 予測科学研究チーム 客員研究員)
ルチアーノ・ヴィダル (理化学研究所 数理創造研究センター (iTHEMS) 数理展開部門 予測科学研究チーム 客員研究員)

Title: Machine learning for precipitation estimation and forecasting Speaker: Dr. Juan Ruiz (University of Buenos Aires – CONICET) Abstract: Estimating and forecasting precipitation is essential for a wide range of human activities as well as for disaster prevention. In this talk we will discuss the application of deep neural networks to the estimation of precipitation with high time and spatial resolution, combining remote sensors and numerical weather predictions. The proposed models show that these information sources can be effectively combined to improve the accuracy of real-time precipitation estimates. Additionally, we will present the application of deep neural networks as a postprocessing tool for short-range deterministic and ensemble-based numerical weather predictions and for the quantification of their uncertainty. The performance of the machine-learning models in the quantification of the uncertainty is close to that achieved by the dynamical ensembles and can be even better in the presence of a model. Title: Analysis of a Long-Lived Supercell: Life Cycle and Severe Weather Patterns in Northern Buenos Aires Province Speaker: Dr. Luciano Vidal (National Meteorological Service, Argentina) Abstract: This work presents a detailed analysis of a long-lived convective supercell that affected the northern Buenos Aires province, Argentina, on March 19, 2024. The primary objective is to characterize its life cycle and associated severe weather patterns using an integrated multi-sensor approach. This methodology combines data from satellite imagery with documentation of surface damage caused by large hail and intense winds. The storm exhibited a remarkable longevity, traveling approximately 400 km over 5.5 hours and impacting a total of 11 municipalities before its dissipation. Throughout its trajectory, the supercell generated significant damage due to large hail and severe wind gusts that, in some areas, exceeded 150 km/h. Furthermore, the storm ultimately affected the Sarandí-Santo Domingo basin (the pilot basin of the Argentine-Japanese SATREPS/PREVENIR project) by generating flash floods. The results of this analysis provide crucial information for the improvement of forecasting and early warning systems for severe weather events in the region.

会場: Hybrid Format (RIKEN R-CCS room 107 and Zoom)

イベント公式言語: 英語

Topological physics and its interdisciplinary influence

2025年11月12日(水) 13:00 - 14:00

小澤 知己 (東北大学 材料科学高等研究所 (AIMR) 教授)

Topological insulators are materials which do not conduct current inside but do conduct at the surface or the edge. The name "topological" comes from the fact that the "shape" of the wavefunction of electrons in topological insulators show non-trivial twist, which can be mathematically characterized by the language of topology. Alongside the development of the study of topological insulators in solids, analogous phenomena were found to exist also in other systems such as photonics, mechanics, geophysics, and active matter. In this seminar, I discuss how the underlying concept of "topology of states" can have a broad impact applicable to various areas in physics, with some emphasis on my own contribution to the field. I aim to structure the first half of my seminar to be accessible to those outside physics, and latter half to be more specialized, covering cutting-edge results.

会場: セミナー室 (359号室) 3階 359号室とZoomのハイブリッド開催

イベント公式言語: 英語

A genealogy-based framework to infer the demographic history, genetic structure, and phenotype association

2025年11月11日(火) 14:00 - 15:00

Charleston Chiang (Associate Professor, University of Southern California, USA)

We propose a conceptual analogy in population genetics to the central dogma of molecular biology. While the central dogma describes the flow of information from DNA to RNA to protein, we posit that under neutrality, a population's demography shapes its underlying genealogy, which in turn determines patterns of genetic variation that give rise to phenotypic variation. At the center of this analogous dogma is the genetic genealogies. Recent advances in inferring the Ancestral Recombination Graph (ARG), a complete record of a population's genealogies, have enabled us to develop a suite of methods that interrogates each stage these fundamental and connected components:

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

On the Role of Hidden States of Modern Hopfield Network in Transformer

2025年11月10日(月) 14:00 - 15:00

瀧 雅人 (立教大学 大学院人工知能科学研究科 准教授)

Large language models such as ChatGPT are based on deep learning architectures known as Transformers. Owing to their remarkable performance and broad applicability, Transformers have become indispensable in modern AI development. However, it still remains an open question why Transformers perform so well and what the essential meaning of their unique structure is. One possible clue lies in the mathematical correspondence between Hopfield Networks and Transformers. In this talk, I will first introduce the major developments over the past decade that have significantly increased the storage capacity of Hopfield Networks. I will then review the theoretical correspondence between Hopfield Networks and Transformers. Building on this background, I will present our recent findings: by extending this correspondence to include the hidden-state dynamics of Hopfield Networks, we discovered a new class of Transformers that can recursively propagate attention-score information across layers. Furthermore, we found, both theoretically and experimentally, that this new Transformer architecture resolves the “rank collapse” problem often observed in conventional multi-layer attention. As a result, when applied to language generation and image recognition tasks, it achieves performance surpassing that of existing Transformer-based models.

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