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674 件
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ワークショップ
KEK(-iTHEMS) Theory Workshop 2026
2026年11月25日(水) - 27日(金)
林 博貴 (東海大学 理学部物理学科 教授)
川合 光 (大阪公立大学 南部陽一郎物理学研究所 客員教授)
森 崇人 (総合研究大学院大学 高エネルギー加速器科学研究科 素粒子原子核専攻 博士課程)
中川 大也 (東京大学 大学院理学系研究科 物理学専攻 助教)
重森 正樹 (名古屋大学 大学院理学研究科 理学専攻 物理学第二 教授)
高柳 匡 (京都大学 基礎物理学研究所 教授)
棚橋 典大 (京都大学 大学院理学研究科 学習物理学特別講座 特定准教授)
山岡 起也 (大阪大学 大学院理学研究科 物理学専攻 博士課程)The KEK Theory Workshop is an annual workshop on string theory and quantum field theory. Since 2014, it has been held every winter as an international workshop and has become one of the major annual events in the high-energy physics community in Japan. This year’s workshop will be held on site at the KEK Tsukuba Campus from November 25 to 27, and it will be jointly organized with RIKEN iTHEMS. The workshop this year aims to provide a forum for extensive discussions on recent developments in string theory, matrix models, gauge/gravity duality, black-hole microstates, lattice constructions of chiral gauge theories, and open quantum systems.
会場: Seminar Hall, Building 3, KEK Tsukuba Campus
イベント公式言語: 英語
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セミナーAI and Scientific Discovery
2026年10月19日(月) 14:00 - 15:30
Joseph Ledsam (Google Health Lead, Japan, Google Japan)
Artificial intelligence is having a transformative impact on health and scientific discovery. This presentation will trace the evolution from foundational breakthroughs to the sophisticated capabilities of today's large-scale AI models. It will explore how these advanced systems are creating new possibilities across the healthcare landscape, from accelerating therapeutic development to enhancing diagnostic processes and interpreting complex medical data. The session will also take a deeper look at the future possibilities for AI in health and explore the emerging role of agentic AI in scientific discovery. The core theme is the responsible development of AI to create tools that assist scientists, support healthcare professionals, and empower users. Bio: Dr Joseph Ledsam leads Google Health in Japan, where he works across AI research, digital health and health in Google products. He has led research in medical AI, genomics and drug discovery published in journals including Nature, Nature Medicine and Nature Methods. Before moving to Japan he worked as a medical doctor in the UK, and founded the Health Research and Genomics teams in Google DeepMind. He obtained his medical degree from The University of Leeds, UK, and was a research fellow at University College London during his clinical residency.
会場: 研究本館 435-437号室 (メイン会場) / via Zoom
イベント公式言語: 英語
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講演会・レクチャー
The 11th Intensive Lectures on Quantum Gravity
2026年9月7日(月) - 9日(水)
初田 泰之 (立教大学 理学部 物理学科 准教授)
In the 11th event of the Intensive Lecture Series, organized by the Quantum Gravity Gatherings (QGG) study group at RIKEN iTHEMS, we will have Prof. Yasuyuki Hatsuda from Rikkyo University, who will deliver a three-day lecture series on the analytic methods in black hole perturbation theory. Black hole perturbation theory plays a very important role in the developments of modern physics. For instance, in gravitational wave astronomy, it can describe the ringdown phase during the merger events of binary black holes. As the frequency and decay rate of each quasinormal mode are unique to the remnant black hole, one can test extreme-gravity physics by extracting those modes from the ringdown signal. In addition, the computation of black hole quasinormal modes based on black hole perturbation theory has relations connecting to conformal field theories and even to the computations of tidal Love numbers. With the broad applications, we expect this lecture series to provide fresh perspectives to researchers across a wide range of fields and to inspire new directions in their own research. 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. This event will take place in person only. Target audience: Senior scholars, early-career researchers, and students are all warmly welcome. Registration deadline: July 31, 2026
会場: 研究本館 4階 435-437号室
イベント公式言語: 英語
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コロキウムEfficient iBF: Balanced Integration of Fragmented Matching Markets for Welfare Improvement
2026年9月4日(金) 15:30 - 17:00
小島 武仁 (東京大学 経済学研究科 教授)
Matching markets often suffer from fragmentation, which leads to inefficiency. We model a fragmented market in a school-choice context and offer a practically relevant method for integration. Specifically, each student and school belong to a region, and we allow for inter-regional transfer of students with "balancedness" constraint: a matching is said to be balanced if, for each region, the outflow of students from that region to other regions is equal to the inflow of students from the latter to the former. Using a directed bipartite graph defined on students and schools, we characterize the set of Pareto efficient matchings among those that are individually rational, balanced and fair (efficient iBF). We also provide a class of polynomial-time algorithms to compute such matchings. When each region favors local students in their priority, the outcome of an algorithm from this class weakly improves student welfare upon the outcome where each region independently uses the deferred acceptance mechanism. Various real-life examples of fragmentation are discussed, and we illustrate how our method would address the issue.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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講演会・レクチャーiTHEMS-UTokyo Intensive Lectures on Quantum Gravity
2026年8月31日(月) - 9月2日(水)
川合 光 (大阪公立大学 南部陽一郎物理学研究所 客員教授)
iTHEMS-UTokyo Intensive Lectures on Quantum Gravity (10th Quantum Gravity Gatherings Lecture Series) The 10th QGG Lecture Series is a special three-day installment of the intensive lecture series organized by the Quantum Gravity Gatherings (QGG) study group at RIKEN iTHEMS. This celebratory edition will feature Professor Hikaru Kawai from Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), who will deliver a series of lectures on themes related to quantum gravity. This lecture series will follow a style similar to Prof. Kawai's first QGG lectures, held three years ago at RIKEN (Wako) as the inaugural QGG event, which explored fundamental questions in quantum gravity, string theory, and the quantum universe. A distinctive feature of this 10th installment is that it will take place on the Komaba campus of The University of Tokyo, where one of the iTHEMS satellite offices is located. This will be the first QGG lecture series held outside Wako, with the aim of making the event more accessible to a broader group of participants. Format: Lectures will be given mainly in blackboard style and in English, encouraging active participation and in-depth Q&A discussions. Poster sessions will also be held, giving participants an opportunity to present their own work or topics of interest. These sessions are intended to foster communication and stimulate the exchange of ideas among participants. This event will take place in person only. Target audience: Senior scholars, early-career researchers, and students are all warmly welcome. Registration deadline: July 31, 2026
会場: 21 Komaba Center for Educational Excellence (21 KOMCEE) East Building, Room K214, Komaba Campus, The University of Tokyo
イベント公式言語: 英語
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コロキウムHidden Networks: From Phase Reductions to Effective Network Interactions
2026年8月24日(月) 15:30 - 17:00
Christian Bick (Associate Professor, Department of Mathematics, Vrije Universiteit Amsterdam, Netherlands)
From networks of interconnected neurons in the brain to coupled electrochemical reactions: The collective dynamics of interacting dynamical systems shape the function (or dysfunction) of many systems that are critical for our everyday lives. For coupled oscillatory processes, synchronization is a prime example of emergent collective dynamics. But how oscillators interact is not necessarily obvious from (physical) connections between the oscillators. Here we look at phase reductions as a way to uncover the hidden 'effective' network interactions for coupled oscillators dynamics. On the one hand, these give insight into when oscillators do and do not interact (despite a link). On the other hand, they elucidate when and how nonpairwise higher-order interactions shape synchronization phenomena in coupled oscillator networks.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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セミナー
Loop expansion in polymer field theory: application to phase separation
2026年7月30日(木) 16:00 - 17:00
川名 清晴 (Research Fellow, Korea Institute for Advanced Study (KIAS), Republic of Korea)
Liquid-liquid phase separation underlies phenomena ranging from protein condensate formation to the phase coexistence of synthetic polymers. In this talk, we develop a field theoretic loop expansion in homopolymer systems by identifying the inverse polymer density ρ^{-1} as the Planck constant ℏ in quantum field theory. The 1-loop approximation is known as the random phase approximation (RPA) and has been extensively applied to many (hetero)polymer systems. We calculate the leading-order (2-loop) and next-to-leading-order (3-loop) corrections to the RPA free energy, denoted as RPA+ and RPA++, respectively. Testing the binodal predicted by the RPA+ against molecular dynamics simulations of bead-spring chains with Gaussian pair interactions, we find that the RPA+ qualitatively improves the dilute-phase coexistence density over the RPA, while the critical point error remains comparable to that of the RPA. Our results establish the loop expansion as a systematic route for refining the RPA-based binodal predictions for polymer phase separation. This talk is based on arXiv: 2605.01261.
会場: via Zoom
イベント公式言語: 英語
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セミナー
Unraveling the very early universe with black holes, boson stars, and cannibal stars
2026年7月24日(金) 14:00 - 16:00
小林 洸 (Associate Professor, International School for Advanced Studies (SISSA), Italy)
According to the standard picture of cosmology, the rich structure of our universe began to form roughly 50,000 years after the big bang. In this talk I will explore the possibility that cosmic structures could also have formed in the extremely early universe, within a fraction of a second after inflation. I will show how this early structure formation can give rise to compact objects, including exotic stars and primordial black holes. These relics provide powerful probes of the first instants of cosmic history, especially the reheating epoch, and may even act as seeds for cosmological phase transitions. Note: This seminar is jointly organized by the iTHEMS-phys Study Group and the iTHEMS-ABBL Joint Astro Study Group.
会場: セミナー室 (359号室) / via Zoom
イベント公式言語: 英語
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コロキウム 明日開催第33回 MACSコロキウム
2026年7月17日(金) 14:45 - 18:00
成瀬 元 (京都大学 大学院理学研究科 地球惑星科学専攻 教授)
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)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
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セミナー 明日開催A first step towards Non-Archimedean Geometric Quantization
2026年7月17日(金) 14:00 - 15:30
後藤 慶太 (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)
Calabi--Yau manifolds have long attracted interest from both mathematics and physics, particularly in the context of mirror symmetry, and form an important class of compact Kähler manifolds. A compact Kähler manifold is Calabi--Yau if and only if it admits a Ricci-flat Kähler metric, which we shall call a CY metric. Such a metric is highly analytic in nature, as it is given as the solution to a second-order PDE on the manifold, namely the complex Monge--Ampère equation. When the Calabi--Yau manifold is a complex projective variety, one algebraic approach to understanding this analytically defined CY metric is to approximate it by algebraically defined metrics called balanced metrics. This framework was initiated by Donaldson and is now known as geometric quantization. In this talk, following the spirit of this theory, we consider a non-Archimedean analogue of this approximation theory. More precisely, for a non-Archimedean analytic space associated with a maximally degenerating family of Calabi--Yau manifolds, we study the approximation of the NACY metric, a non-Archimedean analogue of the CY metric, by algebraically defined metrics. In particular, we introduce NA balanced metrics, which are expected to provide such an approximation, and explain that, for totally degenerating families of abelian varieties, NA balanced metrics indeed approximate the NACY metric.
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
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セミナー 本日開催
Visual system and (social) behavior in zebrafish
2026年7月16日(木) 13:00 - 14:00
久保 郁 (理化学研究所 脳神経科学研究センター (CBS) 知覚運動統合機構研究チーム チームディレクター)
Animals make decisions about their actions using sensory information from the external world. Our lab investigates how the brain processes visual information and generates appropriate behavior using the vertebrate model organism, zebrafish. Our research has uncovered the neural circuits required for processing optic flow, a visual cue that animals use to estimate their own motion. We employ a diverse range of techniques, including behavioral tracking, live imaging of neural activity, and molecular and genetic characterization of neuronal cell types. More recently, our research has focused on social behavior, in which groups of animals collectively generate behavioral decisions. In this seminar, I will present our recent work investigating behavioral contagion in zebrafish.
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
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コロキウム
How did we come to be? — Particle Physics for the Next Decades —
2026年7月10日(金) 15:30 - 17:00
村山 斉 (東京大学 カブリ数物連携宇宙研究機構 (Kavli IPMU) 教授 / Professor, Department of Physics, University of California, Berkeley, USA)
Particle Physics is a study of the smallest and the biggest to uncover the fundamental laws that govern the universe. In recent years, both the United States and Europe have been through long-range planning processes. The future plans worldwide include the studies of (1) neutrinos that may have saved us from a complete annihilation, (2) the Higgs boson that keeps us in one piece, (3) dark matter that assembled us from the primordial soup, (4) inflation that created the macroscopic universe, and (5) the exploration of unknown particles and forces. It requires development of mind-boggling technologies.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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セミナー
iTHEMS-FQSP joint seminar “Aspects of Tripartite Haar Random States”
2026年7月8日(水) 10:30 - 12:00
吉田 紅 (Research Faculty Senior Faculty, Perimeter Institute for Theoretical Physics, Canada / 理化学研究所 基礎量子科学研究プログラム 客員主管研究員)
Randomness plays central roles in understanding strongly entangled quantum systems. The foundational result is Page’s theorem: a bipartite Haar random state is nearly maximally entangled. In this talk, I will ask what happens when the system is divided into three parts. We show that tripartite Haar random states have a very different structure: when each subsystem contains fewer than half of the total qubits, no EPR-like bipartite entanglement can be distilled between any pair by local unitaries or local operations. I will discuss several consequences of this observation, including its implications for quantum error correction, complementary recovery, connected entanglement wedges in AdS/CFT, and possible baby-universe degrees of freedom.
会場: 大河内記念ホール (メイン会場) / via Zoom
イベント公式言語: 英語
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セミナー
Thom polynomials relative to prescribed maps around the boundary
2026年7月3日(金) 15:00 - 17:30
田邊 真郷 (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)
Thom polynomials are universal cohomological obstructions to the appearance of singularities of given types in differentiable maps. Introduced by R. Thom in the 1950s, they have been extensively studied ever since. In the first half of this talk, I would like to recall their theory with introduction of algebro-topological materials. In the second half, I would also like to talk about applications of Thom polynomials to topology of non-singular maps. Since this century, various invariants of immersions/embeddings have been expressed in terms of singularities of their extensions (a.k.a. singular Seifert surfaces). However, those formulas are obtained in different forms and remain somewhat scattered. As the first step to unify them, I would like to introduce Thom polynomials relative to prescribed maps around the boundary. As a main result, we show a structure theorem of Thom polynomials relative to framable immersions. In fact, most earlier formulas are summarized as the vanishing of "correction terms" appearing in the structure theorem. This is an advanced seminar for mathematical researchers.
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
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セミナー
Cosmic-ray bath in a past supernova gives birth to Earth-like planets
2026年7月3日(金) 14:00 - 15:15
澤田 涼 (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)
A key question in astronomy is how ubiquitous Earth-like rocky planets are. The formation of terrestrial planets in our Solar System was strongly influenced by the radioactive decay heat of short-lived radionuclides (SLRs), particularly 26 Al (aluminum-26), likely delivered from nearby supernovae. However, current models struggle to reproduce the abundance of SLRs inferred from meteorite analysis without destroying the protosolar disk. We propose the "immersion" mechanism, where cosmic-ray nucleosynthesis in a supernova shockwave reproduces estimated SLR abundances at a supernova distance (~1 parsec), preserving the disk. We estimate that solar mass stars in star clusters typically experience at least one such supernova within 1 parsec, supporting the feasibility of this scenario. This suggests that Solar System─like SLR abundances and terrestrial planet formation are more common than previously thought.
会場: 研究本館 424-426号室
イベント公式言語: 英語
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セミナー
Genome Structural Variation and the Evolutionary Potential of Sex in the Unicellular Green Alga Closterium
2026年7月2日(木) 13:00 - 14:00
川口 也和子 (国立遺伝学研究所 分子生命史研究室 博士研究員)
Genome size varies widely among eukaryotes, even between closely related species and within species. However, we still know relatively little about where such variation originates, how organisms tolerate its potential negative effects, and whether it can contribute to adaptation. In this seminar, I will present our studies on the unicellular green alga Closterium peracerosum–strigosum–littorale complex. I will first show that genome size variation in this alga is largely explained by extensive genome-wide copy number variation, and that gene expression can be buffered against changes in gene copy number. I will then show that a single episode of sexual reproduction can generate substantial variation in population growth rates under dual environmental stressors, with some F1 populations growing even when both parental strains decline. Finally, I will discuss how sexual reproduction may drive rapid evolutionary change not only by reshuffling alleles, but also by rearranging genome structure.
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
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セミナー
Primitive Ideals and Hilbert Space Representations of Quantized Coordinate Algebras of Complex Semisimple Lie Groups
2026年6月26日(金) 16:30 - 18:00
Heon Lee (Postdoc Researcher, Institute for Advanced Study in Mathematics, Harbin Institute of Technology, Republic of Korea)
The primitive ideals of the coordinate algebra $ \mathcal{O} ( G ) $ of a complex semisimple Lie group $ G $ are in bijection with the points of $ G $, via the correspondence assigning to each point of $ G $ the kernel of the associated evaluation homomorphism on $ \mathcal{O} ( G ) $. This establishes a direct link between the algebraic structure of $ \mathcal{O} ( G ) $ and the geometry of $ G $. In this talk, we investigate the quantum analogue of this classical relationship for the $ q $-deformation $ G_q $. Specifically, we establish a sharp dichotomy: primitive ideals in homogeneous Joseph strata arise as kernels of irreducible representations of $ \mathcal{O} ( G_q ) $ by bounded operators on Hilbert spaces, which provide a quantum analogue of evaluation homomorphisms at points of $ G $, whereas those in inhomogeneous Joseph strata do not. This clarifies the extent to which the primitive spectrum of $ \mathcal{O} ( G_q ) $ can be accessed through operator-theoretic methods. We also analyze the semiclassical consequences of this result in light of the fact that the primitive ideals of $ \mathcal{O} ( G_q ) $ are parametrized by the symplectic leaves of the natural Poisson structure on $ G $. This talk is based on joint work with Christian Voigt.
会場: via Zoom / セミナー室 (359号室)
イベント公式言語: 英語
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セミナー
Fermionic modes of D-instanton wormholes from broken local supersymmetry
2026年6月24日(水) 15:30 - 17:00
糸山 浩司 (大阪公立大学 南部陽一郎物理学研究所 特任教授)
In low-energy supergravity treatment of type IIB superstring on general D-instanton wormhole profiles in the bulk, we obtain non-vanishing scalar two-point functions in addition to the vanishing 〈τ＊τ＊〉 that corresponds to the BPS amplitude detected by two D-instantons at their respective boundaries. This is exploited to show that the modes of broken local supersymmetry in the bulk deliver the fermionic (diagonal) modes on the boundaries through the deformation by the form of current-current two point functions propagating on the tree level cylinder geometry. Our treatment is generalizable to multi D-instanton cases and general Euclidean branes.
会場: 研究本館 3階 359号室 (メイン会場) / via Zoom
イベント公式言語: 英語
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セミナー
iTHEMS Cosmology Forum n°6 - Cosmological Collider Physics
2026年6月22日(月) 9:15 - 17:00
Yi Wang (Professor, Department of Physics, Hong Kong University of Science and Technology, Hong Kong)
山口 昌英 (Director, Center for Theoretical Physics of the Universe, Institute for Basic Science, Republic of Korea)
向田 享平 (高エネルギー加速器研究機構 (KEK) 理論センター 助教)
秋津 一之 (R&D, Proxima Technology)This sixth workshop will bring together researchers exploring the physics of the early universe through cosmological collider signatures. Primordial non-Gaussianities generated during inflation provide a unique opportunity to probe heavy particles and high-energy interactions in the early universe, potentially accessing energies much larger than that probed by terrestrial experiments. In recent years, the subject has developed rapidly, incorporating ideas from inflationary cosmology, quantum field theory in curved spacetime, effective field theory, and scattering amplitudes.
会場: 大河内記念ホール
イベント公式言語: 英語
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セミナー
The Virasoro TQFT approach to 3D gravity and the sum over topologies (QuIG Seminar)
2026年6月19日(金) 13:30 - 16:00
Mengyang Zhang (東京大学 カブリ数物連携宇宙研究機構 (Kavli IPMU) 特任研究員)
In the first part of this talk, I will review the construction of Virasoro TQFT from the Chern–Simons formulation of pure AdS_3 gravity and its application to the statistics of two-dimensional holographic CFT data. I will then discuss its extension to three-dimensional de Sitter gravity and its relation to the double-scaled SYK model. In the second part, I will address the issue of topological invariance in Virasoro TQFT. Despite being “topological,” its partition function is not well-defined on arbitrary three-manifolds, distinguishing it from conventional Reshetikhin–Turaev–Witten TQFTs. I will explain how far the standard proofs of topological invariance can be generalized to this framework. Finally, I will comment on the role of the sum over topologies in the 3D gravitational path integral.
会場: via Zoom / 研究本館
イベント公式言語: 英語