Seminar
1063 events
-
SeminarAI and Scientific Discovery
October 19 (Mon) 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
-
Seminar
Genome Language Models: From DNA Sequences to Biological Foundation Models
August 13 (Thu) 15:00 - 16:00, 2026
Minrui Chen (Ph.D. Student, Kyushu University)
Recent advances in protein language models have greatly transformed protein structure prediction, functional annotation, and biomolecular design. In contrast, genome language models aim to learn directly from DNA sequences, which represent a more upstream layer of biological information encoding genes, regulatory logic, variant effects, and evolutionary signals. In this talk, I will introduce the basic motivation and recent progress of DNA and genome language models, including DNABERT, DNABERT-2, HyenaDNA, Evo, Evo 2, and AlphaGenome. I will discuss how different model architectures and tokenization strategies address the challenges of genomic sequence modeling, such as long-range dependencies, multi-scale biological structure, and genome-scale context.
Venue: #359, 3F, Main Research Building (Main Venue) / via Zoom
Event Official Language: English
-
SeminarHow Reputation Sustains Cooperation: Mathematical Theories of Indirect Reciprocity
August 6 (Thu) 15:00 - 16:00, 2026
Yohsuke Murase (Team Director, Mathematical Social Science Team, Division of Applied Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Cooperation among unrelated individuals is a central puzzle in the evolution of social behavior. Indirect reciprocity offers one influential explanation: people help others not only because they expect direct returns, but also because their actions affect their reputation. In this seminar, I will review mathematical theories of indirect reciprocity, focusing on how reputation and social norms can sustain cooperation. I will begin with the classical framework of public assessment, where everyone shares the same view of each individual’s reputation, including the seminal work of Ohtsuki and Iwasa on the “leading eight” social norms. I will then turn to private assessment, where individuals may disagree about others’ reputations, and discuss why synchronization of opinions becomes essential for cooperation. Overall, the seminar aims to provide an accessible overview of how mathematical models allow us to formalize moral judgments—what counts as good or bad behavior—and to understand the evolution of cooperation through reputation.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Loop expansion in polymer field theory: application to phase separation
July 30 (Thu) 16:00 - 17:00, 2026
Kiyoharu Kawana (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.
Venue: via Zoom
Event Official Language: English
-
Seminar
Center-vortex condensation and monopole condensation in 4d gapped phases
July 27 (Mon) 14:00 - 15:30, 2026
Yui Hayashi (JSPS Postdoctoral Research Fellow, Yukawa Institute for Theoretical Physics, Kyoto University)
Two well-known scenarios for quark confinement are center-vortex proliferation and monopole condensation. We consider gauge-invariant criteria for center-vortex condensation and monopole condensation in terms of Z(N) 1-form symmetry. The condensation of a soliton can be characterized by the non-suppression of the partition function with a proper twisted boundary condition, and we utilize this idea for these criteria. With these definitions, we show that gapped phases with the center-vortex condensation necessarily exhibit the monopole condensation.
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359
Event Official Language: English
-
SeminarSome instances where topological illustration induced new mathematics
July 24 (Fri) 16:30 - 18:00, 2026
Sofia Lambropoulou (Professor, School of Applied Mathematical and Physical Sciences, National Technical University of Athens, Greece)
We shall present instances from generalized knot theory, braid theory and their interactions, where illustration promoted understanding and inspired new mathematics. The first instance addresses a question of V.F.R. Jones whether one can make analogous constructions to the (2-variable) Jones polynomial using other braid groups and other types of Hecke algebras. The second instance addresses the question of formulating braid equivalences, analogous to the Markov theorem for classical braids, in settings where we may not even have available algebraic structures for the related braids. The third instance is about the theory of bonded knots and bonded knotoids used for modelling proteins.
Venue: via Zoom / Seminar Room #359, Seminar Room #359
Event Official Language: English
-
Seminar
Unraveling the very early universe with black holes, boson stars, and cannibal stars
July 24 (Fri) 14:00 - 16:00, 2026
Takeshi Kobayashi (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.
Venue: Seminar Room #359 / via Zoom
Event Official Language: English
-
SeminarThe decision intelligence of humans and machines
July 24 (Fri) 10:30 - 11:30, 2026
Petter Holme (Professor, Department of Computer Science, Aalto University, Finland)
The event has been rescheduled from July 22 to July 24. To understand our near-future of artificial intelligence firmly integrated into many levels of social life, a challenge is to understand the differences and similarities between human and AI decision-making. In controlled laboratory settings assessing risk and uncertainty, LLMs demonstrate superhuman efficiency but fundamentally diverge from human behavior through a rigid hyper-rationality and an inability to disengage from obsolete strategies. However, when applied to messy, real-world dilemmas "in the wild," these models pivot to function as highly effective "satisficers". Human subjects consistently prefer this artificial counsel over human peer advice, noting its ability to carefully balance emotional context with logical constraints while actively reducing anxiety and regret. Ultimately, this synthesis shows that while AI can offer near-optimal laboratory performance and therapeutic impact in daily life, they also have a distinct lack of behavioral plasticity that we need to account for in models of the future.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Entanglement suppression for ΩΩ scattering
July 17 (Fri) 15:00 - 16:30, 2026
Katsuyoshi Sone (Ph.D. Student, Graduate School of Science, Tokyo Metropolitan University)
The S-matrix describing the scattering process can be expressed in terms of projection operators onto the allowed spin–flavor channels and the corresponding phase shifts. Using the entanglement entropy in the spin space of the two-particle state, one can define the entanglement power, which quantifies the ability of the S-matrix to generate entanglement in the system. By investigating the conditions under which the entanglement power of the S-matrix is minimized, namely, the conditions for entanglement suppression, one can derive relations among the phase shifts in different spin–flavor channels. Furthermore, by comparing these relations with the interaction Lagrangian, one can identify the underlying symmetries [1,2]. In this work, we apply the entanglement suppression framework to two-baryon scattering involving spin-3/2 baryons in the flavor decuplet [3]. Lattice QCD calculations have shown that the spin-0 ΩΩ system exhibits scattering close to the unitary limit. Combining this result with the relation between the phase shifts obtained from entanglement suppression, we discuss the scattering behavior of the spin-2 ΩΩchannel.
Venue: #445-447, 4F, Main Research Building (Main Venue) / via Zoom
Event Official Language: English
-
SeminarA first step towards Non-Archimedean Geometric Quantization
July 17 (Fri) 14:00 - 15:30, 2026
Keita Goto (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
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.
Venue: Seminar Room #359, Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Artificial Intelligence in New Physics Electroweak Phase Transition Studies
July 16 (Thu) 15:00 - 16:00, 2026
Yang Zhang (Professor, Henan Normal University, China)
The study of electroweak phase transitions in BSM involves complex numerical calculations, large parameter spaces, and the integration of multiple computational tools. In this talk, I will review recent developments in applying artificial intelligence to new physics phase transition studies. First, I will discuss how machine learning methods can accelerate electroweak phase transition studies, including efficient evaluations of phase transition dynamics, such as bounce action calculations, and the exploration of detectable parameter regions for gravitational-wave searches. Then, I will introduce the emerging role of AI agents in scientific workflows, including automated model construction, effective potential generation, and parameter scans. These developments illustrate how AI can transform traditional computational pipelines and provide new possibilities for future high-energy physics research.
Venue: via Zoom
Event Official Language: English
-
Seminar
Visual system and (social) behavior in zebrafish
July 16 (Thu) 13:00 - 14:00, 2026
Fumi Kubo (Team Director, Laboratory for Sensorimotor Integration, RIKEN Center for Brain Science (CBS))
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.
Venue: Hybrid Format (3F #359 and Zoom), Seminar Room #359
Event Official Language: English
-
Seminar
What determines accuracy in matrix projection models?
July 10 (Fri) 14:30 - 15:30, 2026
Richard Shefferson (Professor, Graduate School of Arts and Sciences, The University of Tokyo)
Matrix projection models (MPMs) have grown in complexity as ecologists have sought to include more factors that may influence population size and structure. However, some studies suggest that MPMs may lead to predictions inaccurate enough as to question their overall utility. I used long-term (21-36 year) demographic datasets on 6 herbaceous perennial species to examine and compare the ability of MPMs with different structural characteristics to predict future population size and structure. In absolute terms, almost all models performed poorly. In relative terms, density-dependent, ahistorical stage-based models with simple life histories and fewer stages were most successful in predicting population size. My results indicate that MPMs and IPMs are typically poor predictors of absolute population size and structure, but, when constructed properly, can still be used as useful qualitative predictors of population change.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Multi-field Inflation with spectator Axions
July 9 (Thu) 14:00 - 16:00, 2026
Diederik Roest (Professor, Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Netherlands)
We will review the inflationary paradigm, with a focus on multi-field inflation. We then propose a generic mechanism in which a light axion spectator reshapes inflationary observables through purely gravitational multi‑field dynamics. In this scenario, the axion is frozen during inflation and starts rolling towards the end, inducing a turn in field space and transient tachyonic phases of the isocurvature mode. This generates a nearly scale‑invariant enhancement of the curvature power spectrum, suppressing the tensor‑to‑scalar ratio and shifting the scalar tilt to a weighted combination of adiabatic and entropic tilts at horizon crossing. We show that these effects can reconcile otherwise disfavored inflaton potentials with current CMB constraints, and predict order-one non-Gaussianities.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Sampling Lattice Gauge Theories with Gauge-Equivariant Neural Networks and Diffusion Models
July 8 (Wed) 14:00 - 15:30, 2026
Andreas Ipp (Senior Scientist, Institute for Theoretical Physics, Technische Universität Wien, Austria)
Thomas Ranner (Project Assistant (FWF), Institute for Theoretical Physics, Technische Universität Wien, Austria)Simulating non-Abelian lattice gauge theories using classical Markov chain Monte Carlo (MCMC) methods is often bottlenecked by critical slowing down and topological freezing. Incorporating physical symmetries into machine learning architectures offers a powerful way towards overcoming these computational limitations. In this talk, we present an overview of how gauge-equivariant neural networks can enhance lattice simulations. In the first part, we introduce Lattice Gauge Equivariant Convolutional Neural Networks (L-CNNs), which build local gauge symmetry directly into the network structure. We discuss their ability to learn Wilson loops and highlight their versatility across different applications, such as approximating effective actions. In the second part, we focus on their application in generative modeling: gauge-equivariant diffusion models. Using a Metropolis-adjusted annealed Langevin scheme, these models are designed to generate uncorrelated field configurations. We demonstrate accurate sampling of 2D U(2) and SU(2) theories, showcase recent advancements in scaling up to 4D SU(3) pure gauge theory, and show that these models extrapolate remarkably well to larger lattices and inverse couplings beyond their training regime.
Venue: #445--447, 4F, Main Research Building (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
iTHEMS-FQSP joint seminar “Aspects of Tripartite Haar Random States”
July 8 (Wed) 10:30 - 12:00, 2026
Beni Yoshida (Research Faculty Senior Faculty, Perimeter Institute for Theoretical Physics, Canada / Senior Visiting Scientist, Fundamental Quantum Science Program, RIKEN)
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.
Venue: Okochi Hall (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Overview of quantum error correcting codes
July 7 (Tue) 15:00 - 16:30, 2026
Takaya Matsuura (Postdoctoral Researcher, Quantum Computing Theory Research Team, RIKEN Center for Quantum Computing (RQC))
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Toward an understanding of microbial circulation in the Mongolian nomadic ecosystem
July 6 (Mon) 13:00 - 14:00, 2026
Akari Shinoda (Assistant Professor, Faculty of Environmental, Life, Natural Science and Technology, Okayama University)
I have been studying microorganisms in the Mongolian nomadic ecosystem from several perspectives. First, I seek to characterize the microbial communities in traditional fermented dairy products—most notably airag (fermented mare's milk)—and their features. Second, I am analyzing the relationship between the traditional Mongolian diet and the gut microbiome. Third, focusing on environmental microorganisms (bioaerosols) in regions undergoing desertification, I aim to trace their origins and atmospheric transport. In the course of these studies, I have come to suspect that microorganisms may circulate among humans, livestock, fermented foods, and the environment. In this research, I aim to understand such microbial circulation by combining approaches from each of these perspectives and by investigating the relationships among these elements. In this talk, I will provide an overview of each topic and discuss the potential of an interdisciplinary approach that connects them.
Venue: Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
Thom polynomials relative to prescribed maps around the boundary
July 3 (Fri) 15:00 - 17:30, 2026
Masato Tanabe (Special Postdoctoral Researcher, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
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.
Venue: Seminar Room #359, Seminar Room #359 (Main Venue) / via Zoom
Event Official Language: English
-
Seminar
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
1063 events