イベント検索
654 件
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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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セミナー
Which Cosmological EFTs Survive the UV? A first step from quantum consistency to late-time cosmology
2026年6月15日(月) 10:00 - 11:30
Carlos Pastor-Marcos (Ph.D. Student, ITP, Heidelberg University, Germany)
EFTs for cosmology are one of our best tools to describe possible departures from GR in the Universe we observe. However, not every low-energy theory can arise from a consistent quantum theory at high energies. In this talk, I will discuss how this question can be addressed using asymptotic safety (AS), and how UV consistency can constrain the space of viable modified-gravity EFTs. Instead of treating all EFT parameters as equally possible, we can ask which regions of theory space are connected to a well-defined fixed point in the UV. This provides the first ingredients of a UV-to-IR strategy, restricting the allowed low-energy theories and indicating how quantum-gravity information may reach cosmology. I will first give a pedagogical introduction to AS and the functional RG, focusing on the physical picture rather than technical details. I will then apply the framework to generalized Proca theories, a class of vector–tensor modified-gravity EFTs with relevant cosmological applications, to illustrate how this analysis is performed in practice and how it can constrain viable IR theories. I will close by discussing how UV completion can become a practical guide for cosmology, translating quantum-consistency conditions into phenomenological signatures, from late-time modified gravity to early-universe observables, strong-gravity tests and GW probes.
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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セミナー
Noncritical Conformal Gravity and 4D Liouville Theory
2026年6月12日(金) 15:00 - 16:30
太田 信義 (大阪公立大学 南部陽一郎物理学研究所 客員教授)
We study the quantum aspects of the conformal gravity in four dimensions, specifically addressing a known discrepancy in beta functions between general quadratic curvature theories and conformal gravity, which corresponds to two scalar degrees of freedom. We demonstrate that this mismatch is resolved by carefully introducing gauge-fixing and ghost terms via the BRST symmetry, which effectively adds the two scalar modes. Drawing lessons from two-dimensional quantum gravity and Liouville theory, we proceed to integrate the four-dimensional trace anomaly to derive a consistent Liouville action, which is given by a free-field action for the conformal mode with a consistent conformal anomaly. We give the condition that the BRST transformation is anomaly free. Finally I would like to talk about some application of this theory.
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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セミナー
Quantum Improved Black Holes in Asymptotically Safe Gravity
2026年6月11日(木) 15:00 - 16:30
Chiang-Mei Chen (Professor, Department of Physics, National Central University, Taiwan)
In this talk, I will explore quantum-improved black hole solutions within the framework of asymptotic safety. In this approach, the Newton coupling becomes scale-dependent, necessitating a meaningful identification between the energy scale and a corresponding physical (length) scale to derive observable consequences for black hole spacetimes. I will argue that the requirement of consistency with the first law of black hole thermodynamics provides a physically motivated criterion for this scale-setting, particularly near the event horizon. Applying this principle, we propose a specific identification scheme that leads to a regularized geometry capable of resolving the ring singularity of Kerr black holes.
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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セミナー
Disorder and Defects in Critical Systems
2026年6月8日(月) 13:30 - 15:00
Baishali Roy (Postdoctoral Fellow, Indian Institute of Technology Kanpur, India)
Real critical systems are often constrained by boundaries and affected by impurities. In 3d, the effect of disordered impurities on the boundary can be modeled by a random magnetic field on a two-dimensional defect. In this talk, I will discuss how such disorder affects the Wilson-Fisher fixed point in d=4−\epsilon dimensions. By analyzing the one-loop RG flow of the defect couplings using the replica formalism, we find a non-trivial "dirty" fixed point which represents a new boundary universality class, stabilized by the bulk \phi^4 interaction. Disordered systems at critical points are known to exhibit logarithmic behavior — I will also discuss how operator mixing in the replica limit gives rise to a logarithmic defect CFT in our setup.
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
Membrane Geometry Regulates Phase Morphology in Postsynaptic Condensates
2026年6月4日(木) 14:00 - 15:00
山田 莉彩 (京都大学 大学院理学研究科 生物科学専攻 博士課程)
Biomolecular condensates are generally regarded as membrane-less organelles formed through liquid–liquid phase separation (LLPS). However, some condensates in living cells emerge in close proximity to biological membranes, where spatial confinement and surface geometry can critically influence their organization and function. In this talk, I will discuss recent advances in understanding how membrane association regulates the phase behavior of postsynaptic density (PSD) condensates. Using mesoscale molecular simulations constrained by experimental interaction data, our study reproduced the distinct condensate architectures observed in solution and on membranes. In three-dimensional solution, AMPA receptor/PSD-95 complexes form the condensate core, whereas NMDA receptor/CaMKII complexes localize to the shell. Strikingly, this organization becomes reversed in membrane-associated two-dimensional systems. The analysis revealed that this transition arises from the competition between CaMKII’s large excluded volume and its highly multivalent interactions. While excluded-volume effects dominate in solution, membrane confinement favors specific multivalent interactions, stabilizing distinct receptor nanodomains. These results provide a physical framework for understanding how spatial dimensionality and molecular architecture regulate biomolecular condensates and synaptic organization.
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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セミナーAI and Scientific Discovery
2026年6月3日(水) 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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セミナー 明日開催
Bootstrapping Cosmological Correlators
2026年5月28日(木) 16:00 - 18:00
Mang Hei Gordon Lee (Post-Doctoral fellow, Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, Taiwan)
Currently there are hundreds of models describing inflation, a period of accelerated expansion in our universe. Each model lead to different imprints in cosmological observables, and for the purpose of testing the idea of inflation itself, it is essential to understand which predictions are model independent. This lead to the idea of cosmological bootstrap, a set of constraints from physical principles and symmetries alone. In this talk I will give an overview on the cosmological bootstrap program. I will first explain how locality, unitarity and symmetry can constrain the kinematics of cosmological correlators. I will then talk about some recent progress on constructing positivity bounds on cosmology, which places constraints on the interactions of fields in inflation.
会場: 研究本館 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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セミナー 明日開催Introduction to categorification and link homology
2026年5月28日(木) 14:00 - 15:30
Mikhail Khovanov (Professor, Department of Mathematics, Johns Hopkins University, USA)
Quantum link invariants relate topology in 3 dimensions to mathematical physics and representation theory. They admit liftings to 4-dimensional structures, known as link homology. We will explain how the skein relations for quantum invariants turn into homological structures at this higher level and how semisimple representation theory turns into non-semisimple representations and homological algebra upon categorification.
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 明日開催Towards rock-solid evolutionary genomics
2026年5月28日(木) 13:00 - 14:00
シュパイデル 玲雄 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 数理遺伝学理研ECL研究ユニット 理研ECL研究ユニットリーダー)
I will present an overview of ongoing and future projects in our lab. We aim to understand how human genomes retain information about our evolutionary past; a central goal is to reconstruct a high-resolution history of humans, pushing the limits of what we can learn about our origins, past migrations, and adaptation to changing environments and survival pressures. Our genomes reveal events that would otherwise be lost to history, revealing how evolutionary forces have shaped genetic variation and influence our health today. How can we confidently infer events that occurred tens of thousands of years ago? I will discuss how converging and independent lines of genomic evidence can provide “rock-solid” support for major evolutionary events, including archaic admixture, large-scale migrations across continents, and population bottlenecks, and how we aim to extend these approaches to study the evolutionary history and origins of humans and other species.
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
Singularities of differentiable maps and Thom polynomials
2026年5月22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)
Singularities are locations where something is exceptional. In particular, singularities of differentiable maps are mathematical concepts corresponding to stationary points of functions and apparent contours of surfaces under projection onto the retina. These are unavoidable in general, but important to study the shape of spaces and behavior of maps. The theory for them was initiated by R. Thom in 1950's, and have been deeply studied by many researchers.
会場: 理化学研究所 和光キャンパス (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
Entanglement entropy and conformal bounds for five-dimensional CFTs
2026年5月21日(木) 15:00 - 16:00
Javier Moreno (京都大学 基礎物理学研究所 基研特任助教)
Abstract: The entanglement entropy of spatial regions in odd-dimensional conformal field theories contains a universal constant contribution that encodes important information about the theory. This quantity can be defined in a robust way using mutual information between slightly deformed versions of a given region. In three-dimensional conformal field theories, it is known that this quantity is always positive and bounded from below by the value corresponding to a spherical region. There is also strong evidence that, for any region, its normalized value is maximized by the free scalar theory. In this work, we show that the situation changes significantly in five dimensions. Although the spherical region remains a local minimum under small shape deformations, more general regions can lead to values that become arbitrarily large in magnitude, with either sign. This implies that, in five-dimensional conformal field theories, the quantity is not bounded from above or below. We also demonstrate that the analogous maximization property observed in three dimensions does not hold in five dimensions when considering general regions. Despite this, we find that existing evidence is consistent with a weaker statement: for small deformations of a spherical region, the normalized quantity remains bounded above by the free scalar result across all five-dimensional conformal field theories. This leads to a new conjectured universal bound relating two key physical quantities—the coefficient governing stress-tensor correlations and the sphere free energy—which appears to hold for all currently known examples.
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
Positivity constraints for the gravitational path integral
2026年5月21日(木) 10:00 - 11:50
ガブリエル・ディウバルド (理化学研究所 数理創造研究センター (iTHEMS) 国内外連携・人材育成部門 理研バークレーセンター 特別研究員)
For a quantum theory of gravity to have a well-defined Hilbert space, the inner product between different states of open and closed universes must be positive semi-definite. Positivity however is not manifest in the low-energy effective theory and in fact imposes nontrivial constraints on the theory. Working in the Gravitational Path Integral (GPI) approach, we derive the general set of positivity constraints on the closed and open universe Hilbert spaces. In the case of AdS gravity, open universe positivity in principle follows from CFT unitarity, however the holographic description of closed universes remains unclear. Strikingly, we exhibit positivity of closed universes across many theories and prove that open positivity implies closed positivity, showing that the CFT 'knows' about the closed universe hilbert space. We then analyze positivity constraints on gravitational theories coupled to axions. We present a method to compute off-shell axion wormholes in AdS and flat space which we use to show that positivity is violated if the axion shift symmetry is exact. In low-energy EFTs where these wormholes are perturbatively stable, to restore positivity the wormhole must have a non-perturbative instability due to instantons that breaks the shift symmetry. Positivity then leads to a proof of a sharp version of the Axion Weak Gravity Conjecture A-WGC, including precise numerical constants. For the QCD axion this provides a bound on the axion decay constant which has phenomenological and experimental consequences for axion searches. In string theory, positivity gives a bound on the coupling between the axion and the dilaton in the low energy effective action.
会場: via Zoom
イベント公式言語: 英語
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セミナー
Sexual conflict over floral receptivity? — theory-guided experiments of evolutionary ecology
2026年5月14日(木) 16:00 - 17:00
京極 大助 (奈良女子大学 研究院自然科学系 准教授)
The theory of evolutionary biology predicts that the interests (in terms of adaptation) of different individuals can conflict with one another. Specifically, mating partners can have different optima in traits such as mating rates, number of mates, number of offspring, and resource allocation to the offspring. Botanists have long recognized that pollination induces floral closure or wilting, which is typically seen as the adaptation of the pollen recipients (i.e., getting rid of costly flowers after achieving their function). However, it is also possible that floral closure or wilting is, at least in part, the outcome of the manipulation by selfish pollen. For example, pollen may secure their paternity by preventing additional pollination. Fewer seed production by the recipients can result in so much allocation of maternal resources to each fertilized egg cell that is maternally maladaptive (but paternally adaptive). Being guided by these theoretical predictions, I have been testing the hypothesis using both Taraxacum dandelions and Arabidopsis. In this talk, I will show our recent (mostly unpublished) results. Although the projects are halfway, results so far generally support the hypothesis. The ideas of related future projects and the philosophy behind the projects may also be discussed.
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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セミナー
Tropical geometry as a tool in algebraic geometry and beyond
2026年5月13日(水) 15:30 - 17:00
Paul Alexander Helminck (Assistant Professor, Mathematical Institute of the Polish Academy of Sciences, Poland)
Tropical geometry is a field in mathematics that lies at the interface of algebraic geometry and combinatorics. One of the main goals in tropical geometry is to uncover the combinatorial patterns hidden in algebraic geometry. This basic principle can already be found in Bézout’s theorem, which counts the roots of sufficiently generic polynomial equations, and its generalization in the form of the BKK theorem, both of which can be proven tropically. The abstract combinatorial ideas that come out of this study have since also seen applications in economics, machine learning, chemical reaction networks and mathematical physics, among others. In this talk I will give an introduction to tropical geometry and I will discuss some of the main results. I will also discuss some of my latest work on finding the topology of an algebraic variety using tropical methods. In particular, I will discuss how this gives rise to a CW complex structure on a K3 surface. This structure for instance gives us a quick way to see various phenomena from mirror symmetry such as the monodromy of integral affine structures.
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
非平衡量子多体系の普遍則：理解から制御へ
2026年5月12日(火) 15:00 - 16:00
濱崎 立資 (理化学研究所 開拓研究本部 (CPR) 濱崎非平衡量子統計力学理研白眉研究チーム 理研白眉研究チームリーダー)
(この講演は日本語で行われます。またこのセミナーは開拓研究所レクチャーシリーズの一環とも位置付けられています) 近年、量子シミュレータや量子コンピュータの発展により、量子多体系を高精度に実現・操作し、そのダイナミクスを直接観測することが可能になった。これにより、「ミクロな量子力学に基づいてマクロな統計力学を理解する」という、von Neumann以来の基礎的問題が改めて注目を集めている。他方で、こうした系を制御することでその量子性を活用し、古典系を凌駕するデバイスや機能を実現しようとする機運も高まっている。 本講演では、ミクロな量子ダイナミクスから非平衡量子多体系の普遍則を理解し、その制御可能性を理論的に明らかにするという観点から、我々の研究と今後の展望を議論する。特に、開放量子多体系に特有の相の特徴づけ、閉じた量子系における熱統計力学の発現、非平衡ダイナミクスにおける厳密な普遍則の成立といった話題を取り上げる。さらに、これらの知見を踏まえ、制御の統計物理学・多体物理学という未開拓領域をいかに切り開くかを展望する。また、この非平衡統計力学の普遍的枠組みが、量子物性にとどまらず他分野へも適用可能であることについても触れたい。
会場: 理化学研究所和光キャンパス 本部棟2階大会議室
イベント公式言語: 日本語
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セミナー
Six operations in differential topology
2026年5月8日(金) 15:00 - 17:00
前川 拓海 (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)
The formalism of six operations, pioneered by Grothendieck and Verdier, serves as a unifying framework for studying cohomological phenomena. This language realizes Poincaré-type duality and transfer maps as certain adjunctions between stable $\infty$-categories of sheaves. In this talk, we highlight the theory of six operations in topology and apply it to provide an intrinsic version of the Pontryagin-Thom construction. We then discuss the intrinsic construction of invariants coming from Seiberg-Witten theory, which is based on the speaker's previous work.
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
Cautionary tales in data analysis from gravitational-wave astronomy
2026年4月23日(木) 13:00 - 14:00
キップ・カンノン (東京大学 ビッグバン宇宙国際センター (RESCEU) 教授)
We'll look at signal detection in noisy data, and at Bayesian inference in astrophysical inverse problems. We'll look at the form these problems take in the context of gravitational-wave astronomy, but we'll focus on where attempts at solutions have gone wrong. The mistakes we make transcend disciplines, and hopefully by shining light on them others can be helped to avoid making them as well.
会場: 研究本館 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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セミナー
Seeing Photons, from Einstein to Bohr to Hanbury Brown-Twiss and related Hong-Ou-Mandel Interference Phenomena
2026年4月22日(水) 15:00 - 16:30
ゴードン・ベイム (Professor Emeritus, University of Illinois, USA)
Why do we believe that the electromagnetic field is quantized, and photons exist? This talk will focus on two ways that the quantization of the electromagnetic field manifests itself in interference experiments. Bohr, who initially doubted photons after Einstein's initial proposal of the photon to explain the photoeffect, eventually proposed a thought experiment showing that the consistency of elementary quantum mechanics at the level of two slit diffraction requires the quantization of the electromagnetic field. In addition, as I will argue, both Hanbury Brown-Twiss interferometry and the closely related Hong-Ou-Mandel effect provide yet another way to see that the electromagnetic field must be quantized.
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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特別講演会
iTHEMS × academist オンラインイベント「数理で読み解く科学の世界 2026」
2026年4月18日(土) 10:00 - 15:30
小泉 淳之介 (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)
福島 理 (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)
洪 木子 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 特別研究員)
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)「数理で読み解く科学の世界」は、2020年より毎年4月に開催しているオンラインイベントです。主催のiTHEMSは、「数学」を共通言語として、物理、生物、宇宙などさまざまな科学分野の横断的な研究をしており、イベントでは、iTHEMS所属の若手研究者4名が最先端の研究について中学生や高校生にもわかるように30分程度の講演を行います。また、一般参加者からの質問やコメントを受け付ける時間も設けています。 詳細、参加お申し込みは、関連リンクをご覧ください。 日時：2026年4月18日（土）10:00〜15:30（開場 9:45） 場所：Web会議サービス「Zoom」（申込者に事前に招待URLをお伝えいたします） 参加費：無料 対象者：中学生・高校生、社会人（どなたでもご参加いただけます） 主催：iTHEMS 共催（企画・運営・宣伝）：アカデミスト株式会社 特別協力：NPO法人 数理の翼 タイムスケジュール： 10:00～ 開始の挨拶・イベント概要説明 10:15～ 講演「幾何学的に見る整数論の世界」小泉 淳之介 博士 11:15～ 講演「対称性がつむぐ量子のふるまい」福島 理 博士 12:10～ 昼休み企画 「AI時代の知性と学び −甘利俊一×磯暁」 出演：甘利 俊一 博士（理研栄誉研究員、帝京大学先端総合研究機構 特任教授）、磯 暁 博士（理研 iTHEMS センター長） 進行：篠崎 菜穂子（フリーアナウンサー） 13:05～ 講演「宇宙の始まりとインフレーション理論」洪 木子 博士 14:05～ 講演「AIと進化で考える生命のしくみ ― 遺伝子ネットワークから生まれる遺伝の法則 ―」大窪 健児 博士 15:00〜 アフタートーク 15:30 終了予定
会場: via Zoom
イベント公式言語: 日本語