't Hooft anomaly matching and symmetry enforced gaplessness

June 1 (Mon) 13:00 - 14:00, 2026

Kantaro Ohmori (Senior Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

I will talk about the 't Hooft anomaly matching and its enforcement of gaplessness. I will also briefly touch on my recent work with Takamasa Ando on this topic.

Venue: via Zoom

Event Official Language: English

Generative diffusion model with inverse renormalization group flows

June 2 (Tue) 14:00 - 15:00, 2026

Kanta Masuki (Ph.D. Student, Graduate School of Science, The University of Tokyo)

Diffusion models have recently emerged as one of the most powerful frameworks for generative modeling, achieving remarkable success in a wide range of domains, including image generation, audio synthesis, and scientific data generation. However, despite their empirical success, conventional diffusion models often require many denoising steps and do not explicitly exploit the multiscale structure naturally present in various types of data. This limitation motivates us to ask whether ideas from the renormalization group (RG), which is designed to describe scale-dependent effective degrees of freedom, can provide a useful principle for constructing more efficient generative models. In this talk, I will present our recent work on renormalization-group diffusion models (RGDMs) [1], a generative framework that connects diffusion models with RG flows. By establishing a correspondence between diffusion dynamics and exact RG flow equations, we construct a diffusion model whose reverse process generates data in a coarse-to-fine manner, thereby effectively reversing an RG flow. I will first introduce the theoretical formulation of RGDMs and explain how the RG perspective leads to a coarse-to-fine generative process. I will then present numerical results in protein structure prediction and image generation, where RGDMs improve sample quality and/or sampling efficiency compared with conventional diffusion models. Finally, I will discuss possible extensions and open questions, including broader applications of RG-inspired generative modeling.

Venue: Seminar Room #359

Event Official Language: English

Lectures on Quantum Measurement Theory: I

June 2 (Tue) 15:30 - 17:00, 2026

Masanao Ozawa (Professor Emeritus, Nagoya University)

Lecture I: Conventional approach: Repeatability, Heisenberg’s original uncertainty principle, and the SQL for gravitational-wave detection The conventional approach to quantum measurement theory taken by von Neumann (1932), Dirac (1958), and Schrödinger (1935) assumes the "repeatability hypothesis" stating that if a physical quantity is measured twice in succession, then the same value is obtained each time, which is often quantitatively generalized to the "approximately repeatable hypothesis" stating that after a measurement of a physical quantity with error ε, the post-measurement deviation around the measured value is no larger than ε; this is equivalent to saying that the state after obtaining a measurement result with error ε becomes an ε-approximate eigenstate corresponding to that measurement result. From the approximate repeatability hypothesis, one can derive "Heisenberg’s original formulation of the uncertainty principle," namely, that when position and momentum are approximately measured simultaneously, the product of their respective errors is at least ℏ/2 (Heisenberg 1927, Kennard 1927, Ozawa 2015), as well as the "standard quantum limit (SQL) for monitoring the free-mass position", which states that when the position of a free mass m is measured at a time interval τ, the result of the second measurement cannot be predicted with uncertainty smaller than (ℏτ/ m)^{1/2} (Caves 1985). The last result leads to a sensitivity limit for interferometric gravitational-wave detectors, and in the early 1980s it was therefore argued that gravitational waves of the expected strength could not be observed using interferometric detectors (Braginsky et al. 1980, Caves et al. 1980).

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

AI and Scientific Discovery

June 3 (Wed) 14:00 - 15:30, 2026

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.

Venue: #435-437, Main Research Building (Main Venue) / via Zoom

Event Official Language: English

Membrane Geometry Regulates Phase Morphology in Postsynaptic Condensates

June 4 (Thu) 14:00 - 15:00, 2026

Risa Yamada (Ph.D. Student, Division of Biological Sciences, Graduate School of Science, Kyoto University)

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.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

DeepQuark: A Deep-Neural-Network Approach to Multiquark Bound States

June 4 (Thu) 15:00 - 16:00, 2026

Wei-Lin Wu (Ph.D. Student, School of Physics, Peking University, China)

Recent discoveries of multiquark candidates have opened a new frontier in hadron spectroscopy and nonperturbative QCD. Understanding these multiquark states poses a challenging quantum many-body problem governed by SU(3) color interactions. Traditional approaches based on basis expansions often encounter severe bottlenecks as the system size and dynamical complexity increase. In this talk, I will present DeepQuark, a deep-neural-network-based variational Monte Carlo framework for solving multiquark bound states. I will discuss the general methodology behind neural-network quantum states, the challenges of extending existing approaches from electronic and nuclear systems to hadron physics, and the architecture of DeepQuark. By combining physics-informed symmetry constructions with the expressive power of deep neural networks, DeepQuark provides a scalable framework for studying multiquark spectroscopy and exploring confinement dynamics.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

reflection positivity in de Sitter space

June 5 (Fri) 10:30 - 11:30, 2026

Yuki Suzuki (Ph.D. Student, Yukawa Institute for Theoretical Physics, Kyoto University)

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Disorder and Defects in Critical Systems

June 8 (Mon) 13:30 - 15:00, 2026

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.

Venue: #359, 3F, Main Research Building (Main Venue) / via Zoom

Event Official Language: English

Mode Estimation in the Space of Phylogenetic Trees with Applications to Species Tree Reconstruction

June 11 (Thu) 13:00 - 14:00, 2026

Yuki Takazawa (Project Research Associate, Graduate School of Information Science and Technology, The University of Tokyo)

Analyzing samples of phylogenetic trees arises in many settings, including bootstrap tree sets, Bayesian posterior samples, and collections of gene trees. The Billera–Holmes–Vogtmann (BHV) tree space provides a geometric framework in which such samples can be viewed as point clouds in a common metric space. A fundamental summary in this space is the Fréchet mean, but it has a property known as stickiness: mean trees tend to lie on lower-dimensional boundaries of the space, corresponding to unresolved, non-binary trees. This behavior can be undesirable, as the mean may then fail to represent the center of interest. In this talk, I will introduce the BHV tree space framework and discuss mode estimation as an alternative way to summarize distributions of phylogenetic trees. After motivating the use of the mode, I will present simple approaches to mode estimation and discuss their consistency and robustness properties. I will then discuss how these ideas can be applied to species tree reconstruction from conflicting gene trees. To handle larger taxon sets, I will use quartet-based aggregation, in which local modal summaries are constructed from trees restricted to sets of four taxa and then combined to reconstruct a species tree. This approach provides a scalable way to apply mode estimation to trees with many taxa and helps reduce the influence of contamination in gene tree collections, as illustrated in simulation studies.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Quantum Improved Black Holes in Asymptotically Safe Gravity

June 11 (Thu) 15:00 - 16:30, 2026

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.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Testing quantum gravity

June 12 (Fri) 10:30 - 12:00, 2026

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.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Noncritical Conformal Gravity and 4D Liouville Theory

June 12 (Fri) 15:00 - 16:30, 2026

Nobuyoshi Ohta (Visiting Professor, Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), Osaka Metropolitan University)

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.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Which Cosmological EFTs Survive the UV? A first step from quantum consistency to late-time cosmology

June 15 (Mon) 10:00 - 11:30, 2026

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.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Prediction of viral evolution and exploration of next-pandemic viruses

June 15 (Mon) 15:00 - 16:00, 2026

Jumpei Ito (Professor, Research Institute for Microbial Diseases, The University of Osaka)

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.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

De Sitter Holography Meets Non-Hermitian Quantum Matter

June 16 (Tue) - 18 (Thu) 2026

Tadashi Takayanagi (Professor, Yukawa Institute for Theoretical Physics, Kyoto University)
Takato Mori (Ph.D. Student, Department of Particle and Nuclear Physics, School of High Energy Accelerator Science, The Graduate University for Advanced Studies (SOKENDAI))
Tomoki Ozawa (Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)
Yuichiro Tada (Designated Assistant Professor, C-Lab, Department of Physics, Institute for Advanced Research, Nagoya University)
Zimo Sun (Postdoc, Institute for Advanced Study in Princeton, USA)
Masataka Watanabe (Assistant Professor, Department of Physics, Graduate School of Science, The University of Tokyo)
Zixia Wei (Junior Fellow at Society of Fellows, Harvard University, USA)
Masaru Hongo (Associate Professor, Department of Physics, Faculty of Science, Niigata University)
Chang Po-Yao (Assistant Professor, Department of Physics, National Tsing Hua University, Taiwan)
Jiro Soda (Professor, Department of Physics, Graduate School of Science, Kobe University)
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.

Venue: Okochi Hall (Main Venue) / via Zoom

Event Official Language: English

Lectures on Quantum Measurement Theory: II

June 16 (Tue) 15:30 - 17:00, 2026

Masanao Ozawa (Professor Emeritus, Nagoya University)

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.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

iTHEMS Cosmology Forum n°6 - Cosmological Collider Physics

June 22 (Mon) 9:15 - 17:00, 2026

Yi Wang (Professor, Department of Physics, Hong Kong University of Science and Technology, Hong Kong)
Masahide Yamaguchi (Director, Center for Theoretical Physics of the Universe, Institute for Basic Science, Republic of Korea)
Kyohei Mukaida (Assistant Professor, Theory Center, High Energy Accelerator Research Organization (KEK))
Kazuyuki Akitsu (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.

Venue: Okochi Hall

Event Official Language: English

Gravitational Properties of the Monopole Bag

June 23 (Tue) 13:30 - 15:30, 2026

Yu Komiya (Ph.D. Student, Yukawa Institute for Theoretical Physics, Kyoto University)

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

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Lectures on Quantum Measurement Theory: III

June 23 (Tue) 15:30 - 17:00, 2026

Masanao Ozawa (Professor Emeritus, Nagoya University)

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.

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Primitive Ideals and Hilbert Space Representations of Quantized Coordinate Algebras of Complex Semisimple Lie Groups

June 26 (Fri) 16:30 - 18:00, 2026

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.

Venue: via Zoom / Seminar Room #359

Event Official Language: English

Phase Transitions as the Breakdown of Statistical Indistinguishability

June 29 (Mon) 15:00 - 16:00, 2026

Hideyuki Miyahara (Associate Professor, Graduate School of Information Science and Technology, Hokkaido University)

We introduce a novel characterization of phase transitions based on hypothesis testing. In our formulation, a phase transition is defined as the breakdown of statistical indistinguishability under vanishing parameter perturbations in the thermodynamic limit. This perspective provides a general, order-parameter-free framework that does not rely on model-specific insights or learning procedures. We show that conventional approaches, such as those based on the Binder parameter, can be reinterpreted as special cases within this framework. As a concrete realization, we employ a distribution-free two-sample run test and demonstrate that the critical point of the two-dimensional Ising model is accurately identified without prior knowledge of the order parameter.

Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359

Event Official Language: English

Lectures on Quantum Measurement Theory: IV

June 30 (Tue) 15:30 - 17:00, 2026

Masanao Ozawa (Professor Emeritus, Nagoya University)

Lecture IV: Instruments in classical mechanics, quantum field theory, and cognitive science In algebraic quantum field theory, measurements describable by interactions between the field and the measuring apparatus are characterized by the class of completely positive instruments that satisfy the condition called the normal extension property (NEP) (Okamura-Ozawa 2016). In classical mechanics, traditionally only non-invasive measurements—those with trivial interaction—were considered admissible, for the observability of the trajectory of motion. Here, however, the full class of measurements realizable by classical-mechanical interactions is characterized in terms of instruments with NEP for the basis of the study of invasive measurements of classical systems. Cognitive processes are also represented by completely positive instruments, along with the long-standing paradigm provided by von Helmholtz, who described a sensation-perception process as a sort of measuring interaction and referred to it as an unconscious inference. This framework is used to show the compatibility of the question order effect and the response replicability effect (Ozawa-Khrennikov 2019), which failed to be explained in an earlier approach using only projective measurement models. It is shown that there exists an instrument model, realizing both the question order effect and the response replicability effect, that is also capable of almost faithfully reproducing public-opinion survey data such as the well-known Clinton-Gore survey by Gallup in 1997 (Ozawa-Khrennikov 2021).

Venue: Seminar Room #359 (Main Venue) / via Zoom

Event Official Language: English

Cosmic-ray bath in a past supernova gives birth to Earth-like planets

July 3 (Fri) 14:00 - 15:15, 2026

Ryo Sawada (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

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.

Venue: #424-426, Main Research Building

Event Official Language: English

How did we come to be? — Particle Physics for the Next Decades —

July 10 (Fri) 15:30 - 17:00, 2026

Hitoshi Murayama (Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo / 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.

Venue: Okochi Hall (Main Venue) / via Zoom

Event Official Language: English

iTHEMS-UTokyo Intensive Lectures on Quantum Gravity

August 31 (Mon) - September 2 (Wed) 2026

Hikaru Kawai (Visiting Professor, Nambu Yoichiro Institute of Theoretical and Experimental Physics (NITEP), Osaka Metropolitan University)

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

Venue: 21 Komaba Center for Educational Excellence (21 KOMCEE) East Building, Room K214, Komaba Campus, The University of Tokyo

Event Official Language: English

Majorana Modes: Fundamentals, Status & Directions

October 13 (Tue) - 16 (Fri) 2026

Workshop Overview Majorana modes lie at the heart of contemporary condensed-matter physics, exhibiting non-Abelian exchange statistics; when protected by topology, they are robust against environmental perturbations. Here, “Majorana mode” is used broadly to include a localized zero-energy Majorana state (a Majorana zero mode) and chiral Majorana edge states with gapless dispersion crossing zero energy. This three-day in-person workshop returns to fundamentals and open questions. It opens with a tutorial session on the afternoon of October 13 for non-experts and adjacent fields, and emphasizes rigorous theory–experiment dialogue, robust methodology, and concrete benchmarks for realizing and testing Majorana modes. Participants Experimentalists and theorists working on Majorana modes Researchers in adjacent fields (quantum materials, superconductivity, mesoscopic physics) Graduate students and postdocs interested in entering the field Topics include (non-exhaustive) Majorana zero modes in a variety of nanostructures Chiral Majorana edge states in quantum spin liquids and other platforms Disorder, interactions, and realistic device modeling Experimental diagnostics and “smoking gun” signatures Topological Quantum Spin Systems

Venue: Okochi Hall

Event Official Language: English