170件のイベント / 2026年
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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
Symmetry origin of the quantum-classical transition, hydrodynamics, and decodability.
2026年6月26日(金) 14:00 - 16:00
Cenke Xu (Professor, University of California, Santa Barbara, USA)
We discuss the following question: when a quantum system evolves into classical one, is there a sharp transition? We will show that the “strong-to-weak” spontaneous symmetry breaking (SW-SSB) provides a sharp onset of classical physics. We present the theoretical framework and summarize recent experimental progress toward observing SW-SSB. We will also discuss the consequence of the SW-SSB, including the emergence of hydrodynamics, and also its information aspect, such as the transition of decodability and distinguishability. Much of the theoretical analysis maps to a problem of defect in the Euclidean spacetime.
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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その他
Mathematical Application Research Team Meeting #16
2026年6月26日(金) 10:30 - 12:00
池 祐一 (東京大学 大学院数理科学研究科 准教授)
Mathematical Application Research Team is honored to invite Prof. Yuichi Ike from the University of Tokyo to this meeting. Everyone is welcome to join the meeting to listen to his seminar. Title: Persistent Homology: Theory and Applications Abstract: Persistent homology is one of the main tools in topological data analysis (TDA), encoding the topological features of given data into persistence diagrams, which are multisets in two-dimensional space. It has been successfully applied to various fields such as materials science and computer graphics. In this talk, I will provide an overview of persistent homology from both theoretical and practical viewpoints. I would also like to discuss persistent-homology-based loss functions, which can be used to control the topological structure of parameters in machine learning.
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
Classical and quantum computing of Nash equilibria of two-player games
2026年6月25日(木) 10:30 - 11:30
エリック・ローツステット (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)
Nash equilibrium is an important concept in game theory. However, finding mixed-strategy Nash equilibria is computationally hard even for relatively small games. I will review some aspects of the numerical computation of Nash equilibria of two-player games including the Lemke-Howson algorithm. I will also discuss preliminary attempts at solving the Nash equilibrium problem on a quantum computer by the quantum approximate optimization algorithm.
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
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
Machine-learned fixed-point actions and observables for SU(3) lattice gauge theory
2026年6月24日(水) 10:30 - 11:30
Müller David (Postdoctoral Researcher, Institute for Theoretical Physics, TU Wien, Austria)
Lattice regularization is the established approach for studying non-perturbative phenomena in quantum chromodynamics, but accurate predictions for the continuum theory remain challenging because standard actions exhibit large lattice artifacts. The renormalization group on the lattice provides a way of suppressing these artifacts: classically perfect fixed-point (FP) actions. In this talk, I show how gauge-equivariant neural networks yield accurate parametrizations of FP actions. Using these machine-learned actions, we perform Monte Carlo simulations to measure gradient-flow scales with highly suppressed artifacts compared to unimproved actions. I will also present preliminary results for machine-learned FP observables to improve the extraction of the topological susceptibility in four-dimensional SU(3) gauge theory.
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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講演会・レクチャー
Lectures on Quantum Measurement Theory: III
2026年6月23日(火) 15:30 - 17:00
小澤 正直 (名古屋大学 名誉教授)
Lecture III: Measurement error, disturbance, the universally valid reformulation of Heisenberg’s uncertainty principle, and a quantitative generalization of the Wigner–Araki–Yanase theorem Definitions of measurement error and disturbance are introduced (Ozawa 2002, 2019) and it is shown that there exists a solvable model for a physically realizable measurement that serves as a counterexample both to Heisenberg’s uncertainty principle in the conventional formulation and to the SQL (Ozawa 1988, 1989, 2002). Thus, those limits are no more considered as universal limits. In fact, the above counter example to SQL was found in 1988 using the idea of contractive state measurements by Yuen (1983) and the LIGO was started in 1994 to succeed in the gravitational wave detection in 2015 as announced in 2016. New formulations are then proved for the uncertainty principle concerning the errors in the approximate simultaneous measurement of two physical quantities, called the "joint error relation" (Ozawa 2003b, 2004), and for the uncertainty principle concerning the error and disturbance associated with the measurement of a single physical quantity, called the "error-disturbance relation" (Ozawa 2003a). From the error-disturbance relation, a quantitative relation for measurement error under an additive conservation law is proved (Ozawa 2002a, 2003b), generalizing the "Wigner–Araki–Yanase theorem" (Wigner 1952, Araki-Yanase 1960), which states that a physical quantity not commuting with a conserved quantity cannot be measured accurately by a measurement interaction satisfying an additive conservation law. The above relation also derives limits for realizing quantum computing and operations under conservation laws (Ozawa 2002b), the results later developed as the resource theory of asymmetry.
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
Gravitational Properties of the Monopole Bag
2026年6月23日(火) 13:30 - 15:30
Yu Komiya (京都大学 基礎物理学研究所 博士課程)
Processes such as phase transitions and symmetry breaking in the early universe are well-studied and thought to be instrumental in giving rise to the nature and composition that we observe. In particular, axionic cosmologies constitute a class of phenomenologically rich models with symmetry breaking, UV relevance, and potentially detectable consequences. In the case where monopoles are also present in such a background, the axion profile may be deformed; it is possible to construct a "monopole bag" state composed of a central monopole within a closed axion domain wall. We consider the gravitational properties of this hybrid defect, and find a both horizon-less and a black hole-like final state can result as remnants of the monopole-domain wall system after gravitational collapse for different input parameters
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
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
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セミナー
Improving data analysis in biology and in general with Tensor Decomposition
2026年6月18日(木) 13:00 - 14:30
リュカ・ソール (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 特別研究員)
This talk will provide an introduction to the basic principles of tensor decomposition methods, especially CANDECOMP/PARAFAC (CP) decomposition. I will explain how such methods can be used to extract meaningful and interpretable patterns from high-dimensional tensor-structured data, which commonly arises in biology, as well as in a broad range of other scientific domains. These patterns can then be used to gain a better understanding of the phenomena under study. I will also briefly discuss how tensor decomposition methods can be extended for various types of data, focusing in particular on how I have been trying to better model longitudinal data.
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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講演会・レクチャー
Lectures on Quantum Measurement Theory: II
2026年6月16日(火) 15:30 - 17:00
小澤 正直 (名古屋大学 名誉教授)
Lecture II: Modern approach: Quantum instruments, POVMs, measuring processes, intersubjectivity, and value reproducibility The modern approach to quantum measurement theory is based on the "realizability theorem" stating that a measurement is physically realizable if and only if its statistical properties are represented by a completely positive instrument, and this is also equivalent to saying that the measurement can be described by an interaction with a measuring apparatus (Ozawa 1984, 2004). The conventional analysis of a measuring process determines the post-measurement object state by applying the "projection postulate" to the meter measurement in the post-measurement state that "entangles" the object and the apparatus, but the above result has been established without assuming the projection postulate altogether; rather we use only the classical Bayesian probability update rule (Ozawa 1984). We introduce the "intersubjectivity theorem" that states that, when multiple observers simultaneously and statistically correctly measure the same physical quantity, they obtain the same measurement value and the "value reproducibility theorem" that states that a statistically correct measurement correctly reproduces the value of the physical quantity immediately before the measurement (Ozawa 2025). The above three theorems essentially solves the so-called measurement problem, since we eliminate the collapse of the wave function and we establish the reality of the the pre-measurement value of the measured observable to be copied to the meter value and to be recorded by the observer.
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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コンファレンス
De Sitter Holography Meets Non-Hermitian Quantum Matter
2026年6月16日(火) - 18日(木)
高柳 匡 (京都大学 基礎物理学研究所 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)
小澤 知己 (東北大学 材料科学高等研究所 (AIMR) 教授)
多田 祐一郎 (名古屋大学 高等研究院理学研究科C研 特任助教)
Zimo Sun (Postdoc, Institute for Advanced Study in Princeton, USA)
渡邉 真隆 (東京大学 大学院理学系研究科 物理学専攻 助教)
魏 子夏 (Junior Fellow at Society of Fellows, Harvard University, USA)
本郷 優 (新潟大学 理学部 物理学プログラム 准教授)
Chang Po-Yao (Assistant Professor, Department of Physics, National Tsing Hua University, Taiwan)
早田 次郎 (神戸大学 大学院理学研究科 物理学専攻 教授)
Harry Goodhew (Predoctoral Fellow, Department of Physics, National Taiwan University, Taiwan)
Guilherme Leite Pimentel (Associate Professor, Scuola Normale Superiore, Italy)Understanding quantum gravity in de Sitter (dS) space remains a central challenge in cosmology and high-energy theory. While the dS/CFT proposal offers an organizing principle, its dual description is generically non-unitary, forcing us to rethink what we mean by dynamics, observables, and consistency when unitarity is not available. In parallel, condensed-matter theory has developed powerful frameworks for non-unitary physics via non-Hermitian Hamiltonians and field theories, revealing systematic structures such as complex spectra, biorthogonal formalisms, generalized symmetries (e.g., PT/pseudo-Hermiticity), exceptional points, and non-Hermitian topology. This workshop brings these communities together to test whether modern non-Hermitian tools can sharpen dS/CFT: clarifying the interpretation of non-unitary dynamics, identifying dS counterparts of non-Hermitian structures, and formulating concrete cross-field problems that can seed new collaborations.
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
Prediction of viral evolution and exploration of next-pandemic viruses
2026年6月15日(月) 15:00 - 16:00
伊東 潤平 (大阪大学 微生物病研究所 附属バイオインフォマティクスセンター 教授)
One of the major challenges in controlling viral infectious diseases is that viruses continuously alter their properties through evolution. During the COVID-19 pandemic, for example, variants with enhanced immune escape and increased fitness emerged successively, thereby making epidemic control substantially more difficult. In this seminor, I will introduce our research on understanding and predicting viral evolution and epidemic dynamics by integrating protein language models, massive viral genome sequence data, and large-scale experimental datasets to model the relationships among viral genotypes, antigenicity, and fitness. Another major factor complicating the control of viral infectious diseases is the cross-species transmission of viruses harbored by wild animals to humans and livestock, leading to the emergence of novel infectious diseases. The COVID-19 pandemic, for instance, is thought to have originated from a coronavirus carried by horseshoe bats that subsequently spilled over into humans. To prepare for future pandemics, it is essential to comprehensively identify and systematically catalog viruses circulating in wildlife populations. In this seminar, I will also present our research on efficiently discovering novel viruses from massive public RNA-seq datasets by predicting viral infection based on host immune responses.
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
Patient-adaptive medical AI: Similarity-based fine-tuning for cross-patient generalization
2026年6月15日(月) 14:00 - 15:00
趙 旭陽 (大阪大学 大学院医学系研究科・医学部 助教)
Medical AI models often face performance degradation when applied to new patients due to inter-patient variability in physiological characteristics, disease manifestations, and clinical histories. This challenge, commonly referred to as the cross-patient problem, limits the generalizability and clinical applicability of machine learning systems. We introduce a similarity-driven framework for patient-adaptive learning that improves model performance on previously unseen patients. The proposed approach first trains a base model using conventional supervised learning and subsequently estimates the similarity between a target patient and the training population using intermediate model representations. The similarity information is then incorporated into a fine-tuning procedure through patient-dependent weighting, enabling the model to adapt its decision boundaries toward the characteristics of each individual patient. We demonstrate the effectiveness of this strategy in two medical AI applications, including seizure onset zone classification in epilepsy and medical image classification tasks. Experimental results show consistent improvements over standard cross-patient learning approaches, highlighting the potential of similarity-based adaptation as a practical solution for personalized and generalizable medical AI systems.
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
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
Testing quantum gravity
2026年6月12日(金) 10:30 - 12:00
Daniel Carney (Scientist, Lawrence Berkeley National Laboratory (LBNL), USA)
I will give an overview of proposals to test the quantization of the gravitational field using terrestrial experiments. This will include gravitational entanglement experiments, "single-graviton detection" experiments, and searches for anomalous gravitational noise and decoherence.
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
170件のイベント / 2026年