セミナー

Boundary Scattering and Non-invertible Symmetries in 1+1 Dimensions

2025年7月4日(金) 14:00 - 15:00

嶋守 聡一郎 (大阪大学 博士課程)

Recent studies by Copetti, Córdova and Komatsu have revealed that when non-invertible symmetries are spontaneously broken, the conventional crossing relation of the S-matrix is modified by the effects of the corresponding topological quantum field theory (TQFT). We extend these considerations to (1+1)-dimensional quantum field theories (QFTs) with boundaries. In the presence of a boundary, one can define not only the bulk S-matrix but also the boundary S-matrix, which is subject to a consistency condition known as the boundary crossing relation. We show that when the boundary is weakly-symmetric under the non-invertible symmetry, the conventional boundary crossing relation also receives a modification due to the TQFT effects. As a concrete example of the boundary scattering, we analyze kink scattering in the gapped theory obtained from the Φ(1,3)-deformation of a minimal model. We explicitly construct the boundary S-matrix that satisfies the Ward-Takahashi identities associated with non-invertible symmetries. This talk is based on the collaboration with Satoshi Yamaguchi.

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

Exact WKB as unified analytic structure for resonance physics

2025年6月27日(金) 15:00 - 17:00

森川 億人 (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)

We develop a unified framework for analyzing quantum mechanical resonances using the exact WKB method. The non-perturbative formulation based on the exact WKB method works for incorporating well-established phenomenological regularizations, the ABC theorem (proof of the completeness of Hilbert space), and the rigged Hilbert space in resonant phenomena. By examining the inverted Rosen-Morse potential, we illustrate how the exact WKB analysis captures resonant phenomena rigorously. Also, we clarify the corresponding linear spaces defined in each step of the exact WKB manipulations. The complementarity between the essential analyticity for resonance and the ABC theorem leads us to construct a modified Hilbert space called the rigged Hilbert space within the exact WKB framework. This offers a deeper understanding of resonant states and their analytic structures. Our results provide a concrete demonstration of the non-perturbative accuracy of exact WKB methods in unstable quantum systems.

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

Universal Pseudo-Goldstone Damping from the Real-Time Functional Renormalization Group

2025年6月26日(木) 15:00 - 16:00

Yang-Yang Tan (Ph.D. Candidate, Dalian University of Technology, China)

Strongly correlated systems, from QCD matter to condensed matter, exhibit universal dynamics near phase transitions. However, despite the successes of various theoretical approaches, systematic treatments of fluctuations are scarce. This talk unveils a novel universal damping mechanism for pseudo-Goldstone modes in systems with spontaneously broken approximate symmetries. I will introduce the real-time functional renormalization group (fRG) method, a powerful non-perturbative framework for studying real-time dynamics near critical points. Using this approach within a critical O(N) model, we uncover a new universal scaling for pseudo-Goldstone damping. Different from the conventional damping found in holography and hydrodynamics, the new one is controlled by critical fluctuations, hence is invisible in mean-field systems or strongly correlated systems with classical gravity duals. Since the critical damping depends solely on the universalities of the critical point, irrespective of the microscopic details, our conclusion should be applicable to a wide class of interacting systems.

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

Simulating the spread of infection in networks with quantum computers

2025年6月26日(木) 13:00 - 14:00

王 啸洋 (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 特別研究員)

Many classical stochastic processes can be modeled as Markovian processes, including the spreading of infection in networks. Simulating the Markovian processes using classical computers is generally unscalable for large networks. In this seminar, I will introduce the Hamiltonian evolution on quantum computers and how the Markovian spreading of infection can be efficiently simulated using the Hamiltonian evolution. In particular, we analytically and numerically analyze the evolution of a specifically designed Hamiltonian, and prove that the evolution simulates a classical Markovian process, which describes the well-known epidemiological stochastic susceptible and infectious (SI) model. As an example, we simulate the infection spreading process of the SARS-CoV-2 variant Omicron in a small-world network. The simulation results are qualitative consistent with the infection spreading in the west coast of USA.

会場: via Zoom / セミナー室 (359号室)

イベント公式言語: 英語

Generative Models for Statistical Field Theories

2025年6月25日(水) 15:00 - 16:00

王 凌霄 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

In the final talk of the DEEP-IN series, we will explore the role of generative models in learning phase transitions and sampling in lattice systems. First, we demonstrate how generative models can serve as global samplers by learning the underlying probability distributions. This enables the sampling of configurations more efficiently for lattice field theories. We will also demonstrate how the ferromagnetic phase transition, the Kosterlitz-Thouless transition, and quantum phase transitions can be identified from generative models. I will briefly introduce generative diffusion models, which can be interpreted as a stochastic quantization scheme. This opens a new path for understanding deep generative models. This is an informal seminar, we will start with the methodology and some practical examples, and finally reserve time for everyone interested to discuss it together.

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

ComSHeL introductions meeting

2025年6月24日(火) 14:00 - 15:30

Following our Launch Meeting on May 1st, in this second meeting of our study group we plan for each member of the ComSHeL Study Group and anyone who joins us that day to introduce their research briefly to get to know one another's focus and expertise. If you are interested in possibly collaborating with ComSHeL members and/or you would like to get to know some of the researchers who joined us as part of iTHEMS new Division of Applied Mathematical Science, please join us. I extended the duration to 90 min (from our usual 60 min) to make sure we have enough time to hear from everyone. Each attendee will have approximately 4 minutes to explain their past, current, or upcoming research and time will be kept strictly. Time might be adjusted on the day of the meeting based on the number of applicants. If you would like to show some slides (max 3 slides), please prepare them in advance and send them to cbeau@riken.jp in PDF format no later than June 20. But no one should feel they must prepare slides: it is fine to speak freely and informally about your work.

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

LLM-based physics analysis assistant at BESIII

2025年6月23日(月) 15:00 - 16:00

廖 一朴 (Ph.D. Student, Institute of High Energy Physics, Chinese Academy of Sciences, China)

The data processing and analyzing is one of the main challenges at HEP experiments. To accelerate the physics analysis and drive new physics discovery, the rapidly developing Large Language Model (LLM) is the most promising approach, it have demonstrated astonishing capabilities in recognition and generation of text while most parts of physics analysis can be benefitted. In this talk we will discuss the construction of a dedicated intelligent agent, an AI assistant names Dr.Sai at BESIII based on LLM, the potential usage to boost the data analysis. I will also provide a brief overview of the construction of the AI platform at the Institute of High Energy Physics (ai.ihep.ac.cn) and outline the roadmap for AI4HEP. Yipu Liao (廖一朴) is a Ph.D. student at the Institute of High Energy Physics, Chinese Academy of Sciences. His research is centered on particle physics data analysis, with a special emphasis on Charmonium(-like) and tau physics within the BESIII and Belle II experiments. He is actively engaged in the development of the AI assistant project (DrSai) for the BESIII experiment, and leads the design and evaluation of automated processes.

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

Spectral flow and applications

2025年6月23日(月) 14:00 - 16:00

クリストファー・ボーン (名古屋大学 教養教育院 准教授)

Given a family of symmetric matrices indexed by a parameter (e.g. time, external field), changing this parameter will cause the eigenvalues to move along the real axis. The spectral flow tracks these eigenvalues and counts how many cross the point 0. This idea turns out to be very useful for both pure mathematics as well as applications to physics and elsewhere. In this talk, I will introduce the spectral flow and how it can be generalised to a variety of settings that are also relevant for applications in quantum physics.

会場: 研究本館 3階 359号室とZoomのハイブリッド開催 (メイン会場) / via Zoom

イベント公式言語: 英語

Programmed chromosome eliminations in flies

2025年6月19日(木) 13:00 - 14:00

ロバート・バイアード (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 訪問研究員)

Species that break the traditional rules of genetics and inheritance offer perhaps some of the best opportunities to study fundamental biological questions. Sciarids (fungus gnats) are a species-rich family of flies with highly unorthodox chromosome inheritance. Asymmetric male meiotic divisions result in elimination of the paternal genome every generation, and maternally-controlled eliminations of chromosomes in the developing embryo determine offspring sex. I use a combination of genomics, population genetics, and cytogenetics to understand both the mechanisms and the evolution of this system. I will discuss how these approaches have allowed us to uncover some fascinating biology as well as tackle broader biological questions.

会場: via Zoom / 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

Gauge-equivariant multigrid neural networks

2025年6月19日(木) 10:30 - 12:00

Tilo Wettig (Professor, Universität Regensburg, Germany)

In lattice QCD simulations, the most time-consuming element is typically the solution of the Dirac equation in the presence of a given gauge field. The current state of the art is to use a multigrid preconditioner to reduce the condition number of the Dirac operator matrix. We show how such preconditioners can be constructed using gauge-equivariant neural networks. For the multigrid solve we employ parallel-transport convolution layers. For the multigrid setup we consider two versions: the standard construction based on the near-null space of the operator, and a gauge-equivariant construction using pooling and subsampling layers. We show that both versions eliminate critical slowing down.

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

Identifying Lightning Structures and Predicting Cloud Properties

2025年6月18日(水) 15:00 - 16:00

王 凌霄 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

This third talk in the DEEP-IN series focuses on using unsupervised machine learning to identify and predict patterns in atmospheric phenomena. We begin by demonstrating how clustering and dimensionality reduction techniques can uncover coherent lightning patterns from high-dimensional LOFAR (LOw Frequency ARray) data, offering insight into large-scale organization. We then show how generative diffusion models enable super-resolution retrieval of cloud properties for all day from satellite observations. This is an informal seminar, we will start with the methodology and some practical examples, and finally reserve time for everyone interested to discuss it together.

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

A New Holographic Entanglement Entropy in the de Sitter space

2025年6月13日(金) 16:00 - 17:00

鈴木 優樹 (京都大学 基礎物理学研究所 博士課程（学術振興会特別研究員）)

We propose a new holographic entanglement entropy in the three-dimensional de Sitter space. It is known that the holographic entanglement entropy via Ryu-Takayanagi prescription violates the entropic inequalities that they should satisfy. We propose a kind of extensions of the Ryu-Takayanagi formula so that they satisfy the strong subadditivity. We fix consistent parameter regions of the entropy and finally comment on the implications to the static patch holography.

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

From Galaxies to Cosmological Structures: The Multi-Scale Influence of Cosmic Rays

2025年6月13日(金) 14:00 - 15:15

Ellis Owen (理化学研究所 開拓研究所 (PRI) 長瀧天体ビッグバン研究室 基礎科学特別研究員)

Cosmic rays interact with astrophysical systems over a broad range of scales. They go hand-in-hand with violent, energetic astrophysical environments, and are an active agent able to regulate the evolution and physical conditions of galactic and circum-galactic ecosystems. Depending on their energy, cosmic rays can also escape from their galactic environments of origin, and propagate into larger-scale cosmological structures. In this talk, I will discuss the impacts of cosmic rays retained in galaxies. I will show they can deposit energy and momentum to alter the initial conditions of star-formation, modify the circulation of baryons around galaxies, and have the potential to regulate long-term galaxy evolution. I will highlight some of the astrophysical consequences of contained hadronic and leptonic cosmic rays in and around galaxies, and how their influence can be probed using signatures including X-rays, gamma-rays and neutrinos. I will also discuss what happens to the cosmic rays that escape from galaxies, including their interactions with the magnetized large-scale structures of our Universe, and the fate of distant high-energy cosmic rays that do not reach us on Earth.

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

Inferring Castration Status and Age-at-Death from Sheepskin Parchments

2025年6月12日(木) 13:00 - 14:00

キーラン・オコナー (Ph.D. Student, Department of Genetics, Trinity College Dublin, Ireland)

Secondary products such as traction from cattle, wool from sheep, and mobility from horses are invaluable outputs from rearing livestock. The innovative herd management practice of castration enables non-breeding males to be managed safely beyond typical ages of slaughter, greatly improving the productivity of livestock herds. Although osteological methods can identify some morphological differences between castrated and intact males, it is difficult to make clear distinctions between them. However, methylation values are affected by the considerable hormonal changes that occur as a result of castration. For example, castrated male sheep have shown lower biological ages compared to age-matched intact rams (Sugrue et al., 2021). Furthermore, age-at-death has been predicted from reconstructed methylation values in ancient horses, informing on culling practices (Liu et al., 2023). Using an aDNA-specific bisulfite sequencing approach, we have reconstructed CpG methylation values from sheepskin parchments. We have developed machine learning models trained on modern sheep in order to infer traits of interest such as castration and age-at-death. The informative CpG sites have been incorporated into a target capture set to enable cost-effective sequencing of additional samples. This will enable the characterisation of these traits in ancient sheep across time periods, geographical locations, and archaeological contexts.

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

Collective Behaviors and Deep Learning Applications

2025年6月11日(水) 15:00 - 16:00

王 凌霄 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

Understanding and modeling collective pedestrian behavior, particularly under extreme conditions, is a challenging problem that combines cognition, physics, and data analysis. In the second talk of DEEP-IN series, I will explore how deep learning can reveal the underlying principles of crowd dynamics from data. Starting with a bounded rationality framework, we demonstrate how deep learning can quantify evacuation dynamics and reveal hidden patterns in collective motion. Specifically, we demonstrate how macroscopic observables, such as entropy and kinetic energy, can be extracted from microscopic trajectories in simulations and real-world data. This is an informal seminar, we will start with the methodology and some practical examples, and finally reserve time for everyone interested to discuss it together.

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

Quantum Decryption from technological perspective to business opportunities

2025年6月6日(金) 16:00 - 17:30

杉浦 祥 (CEO, BlocQ, Inc.)

Quantum decryption is a foundational application of fault-tolerant quantum computing (FTQC), essential for future cryptographic security. While quantum simulations, especially quantum chemistry, dominate current quantum computing research, quantum decryption remains less explored despite its significance. In this talk, we give a business style talk that overviews the current status of quantum decryption and our company's pioneering efforts to advance practical FTQC-based solutions. We discuss recent technological advancements and outline our strategic initiatives aimed at leading the field toward secure communications.

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

A New Measure of Genuine Multipartite Entanglement

2025年6月6日(金) 14:00 - 15:00

Jaydeep Kumar Basak (Post-doctoral Fellow, Gwangju Institute of Science and Technology (GIST), Republic of Korea)

In this talk, I will introduce Latent entropy" (L-entropy) as a novel measure to characterize genuine multipartite entanglement in pure states, applicable to quantum systems with both finite and infinite degrees of freedom. This measure, derived from an upper bound on reflected entropy, attains its maximum for three-party GHZ states and $n=4,5$-party $2$-uniform states. I will also show the generalization of this measure for higher party states. Furthermore, I will discuss an analogue of the Page curve in multiboundary wormholes. If time permits, I will show the behaviour of multipartite entanglement in random states.

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

Solving Inverse Problems with Physics-Driven Deep Learning

2025年6月4日(水) 15:00 - 16:00

王 凌霄 (理化学研究所 数理創造研究センター (iTHEMS) 数理基礎部門 研究員)

This talk kicks off a four-part seminar series on the DEEP-IN WG, an interdisciplinary working group exploring how modern deep learning — including deep generative models — can tackle inverse problems across scientific domains. In addition to DEEP-IN activities, I will present a new framework and vision, motivated by the growing synergy between physics-driven designs for deep learning and scientific discovery, as discussed in our recent review article. Future talks will demonstrate machine learning applications in collective behaviors, weather systems, and lattice field simulations. This is an informal seminar, we will start with the methodology, give some practical examples, and finally reserve time for everyone interested to discuss it together.

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