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女子中高生のためのセミナーシリーズ「AI時代、中高生は将来に向けて何をすればいいのか？」

2025年1月25日(土) 14:00 - 18:30

理研の革新知能統合研究センター（AIP）と数理創造プログラム（iTHEMS）が共同で、AIや数理・情報の研究に関心のある中高生に向けて、研究者がどのような研究をしているのかを紹介するイベントを企画しました。一緒に 「AIと創る未来」 を考え、今、中高生がすべきことを探ってみませんか？皆様のご参加をお待ちしております！ 詳細は関連リンクをご覧下さい。

会場: 日本橋AIPセンターオープンスペース & Zoom（ハイブリッド開催）

イベント公式言語: 日本語

Quantitative Characterization of the Cellular Physical Properties to Understand the Organ Regeneration and Cancer Progression

2025年1月23日(木) 16:00 - 17:00

松﨑 賢寿 (大阪大学 大学院工学研究科附属フューチャーイノベーションセンター テクノアリーナ准教授 / 大阪大学 大学院工学研究科物理学系専攻応用物理学コース 助教)

Since the discovery of regulating the differentiation of "single" stem cells by extracellular mechanics, researchers have focused on the mechanobiology of single cells. Our collaborative studies provided the first breakthrough to identify optimal mechanics for multi-cellular, liver organogenesis (Takebe, .., Matsuzaki,.., Yoshikawa et al., Cell Stem Cell 2015, Stem Cell Reports 2018). My motivation is to be a pioneer internationally in understanding the role of heterogenic physical properties in multi-cellular related life-phenomena such as cancer cell adhesion (Matsuzaki et al., Phys Chem Chem Phys 2018, Bioconjugate Chem 2023, PNAS 2024, Osaka University Award 2024.), regeneration of colon/muscle (iScience 2022, Taniguchi,.., Matsuzaki et al., Mucosal Immunology 2023, J. Phys Chem Letter 2014, 2022, 2024.), and bone (Mizuno, .., Matsuzaki et al., Stem Cell Res. Ther. 2022, iScience 2024). In my presentation, I will overview the recent progress in developing fluorescence/interference microscopy combining atomic force microscopy (AFM), and its application to organ regeneration and cancer progression.

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

Probabilistic approach to discrete integrable systems

2025年1月17日(金) 15:30 - 17:30

佐々田 槙子 (東京大学 大学院数理科学研究科・理学部数学科 教授)

The KdV equation and the Toda lattice are two central and widely studied examples of classical integrable systems, and many of their variations have been introduced to the present. In particular, the box-ball system (BBS) is a basic example of a discrete integrable system, which has been revealed to be an ultra-discrete version of the KdV equation and the Toda lattice. The BBS has been studied from various viewpoints such as tropical geometry, combinatorics, and cellular-automaton. As a new perspective, research on probabilistic approaches to this system has been rapidly expanding in recent years, including the application of the Pitman transform, analysis of invariant measures and its generalized hydrodynamics. More recently, we find that the application of the Pitman transform and the study of invariant measures of i.i.d.-type also work in the same manner for the discrete KdV equation and the discrete Toda lattice. Further research has begun on the relationship between the Yang-baxter maps and the existence of i.i.d.-type invariant measures for the discrete integrable systems. In this talk, I will introduce these new research topics that have been spreading over the past several years from the basics. This talk is based on several joint works with David Croydon, Tsuyoshi Kato, Satoshi Tsujimoto, Ryosuke Uozumi, Matteo Mucciconi, Tomohiro Sasamoto, Hayate Suda and Stefano Olla.

会場: セミナー室 (359号室)

イベント公式言語: 英語

Principles of the evolution of human social structures: kinship and gift-giving

2025年1月16日(木) 16:00 - 17:15

板尾 健司 (理化学研究所 脳神経科学研究センター (CBS) 計算論的集団力学連携ユニット 基礎科学特別研究員)

Anthropologists have long noted structural similarities among geographically distant societies. To investigate the origins of these patterns, I develop simple models of human interactions based on field observations, simulating the emergence of social structures. This talk focuses on two key topics. The first examines the evolution of kinship structures in clan societies [1, 2, 3]. By modeling kin and in-law cooperation alongside mating competition, I show how cultural groups with specific marriage rules spontaneously emerge. The second explores the transition of social organizations through competitive gift-giving [4, 5]. By modeling how gifts deliver material goods to recipients and confer social reputation upon donors, I demonstrate transitions across four phases—band, tribe, chiefdom, and kingdom—each characterized by distinct social networks and distributions of wealth and reputation. In both cases, I highlight the alignment between theoretical predictions and empirical observations, offering quantitative criteria and empirically measurable explanatory parameters for classifying social structures.

会場: via Zoom / 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

Visit by ASCENT-6E high school students

2025年1月13日(月) 10:40 - 16:00

PROGRAMME Visit of students enrolled in the ASCENT Program at Chiba University Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS): RIKEN Wako Campus (Wako City, Saitama) Event date: Monday, January 13th, 2025 ASCENT-6E Program: iTHEMS members: Schedule 10:30-10:40 (10 min): Arriving procedure 10:40-11:00 (20 min) at meeting room on the 4th floor, Main Research Building Introduction of students (to hear their names and scientific fields of interest). We will provide colour-coded badges to write their names and the colour would represent their field of interest (e.g., blue for biology, green for math, red for physics). 11:00-11:10 (10 min) Bathroom break 11:10-12:00 (50 min) at meeting room on the 4th floor, Main Research Building First set of talks by iTHEMS members (10 min each) Tetsuo Hatsuda (Physics, mathematics) Catherine Beauchemin (Physics, biology) Tsukasa Tada (Physics, mathematics) Gen Kurosawa (Biology) Misako Tatsuuma (Physics) 12:00-12:50 (50 min) at Common Space in the 4th floor of Main Research Building (tentative) Discussion Lunch with students 12:50-13:40 (50 min) at meeting room on the 4th floor, Main Research Building Second set of talks by iTHEMS members (10 min each) Akihisa Yamamoto (Physics, biology) Ryo Namba (Physics) Christy Kelly (Mathematics, physics) Rumi Hasegawa (Physics) Jose Gutierrez (Biology) 13:40-13:50 (10 min) at meeting room on the 4th floor, Main Research Building Brief overview of iTHEMS and RIKEN programmes (T.Hatsuda, C.Beauchemin, or T. Tada) (e.g., JRA, IPA, SPDR, RS/SRS) 13:50-14:00 (10 min) Bathroom break 14:00-14:15 (15 min) at meeting room on the 4th floor, Main Research Building (tentative) Short statements by Prof. Jun Nomura and ASCENT program coordinators Qian Wang and Hina Morishige 14:15-16:00 (105 min) at Common Space in the 4th floor of Main Research Building (tentative) Informal discussions among ASCENT program students and iTHEMS members over some snacks and coffee. iTHEMS members will spread at different areas in the common space of 3rd floor and will display posters or conduct activities that can facilitate discussion. If posters are used, they may be the ones used in the Now & Next or new ones.

会場: 研究本館 4階 435-437号室

イベント公式言語: 英語

Search for BSM particles from high energy supernova neutrinos

2025年1月10日(金) 14:00 - 15:15

秋田 謙介 (東京大学 大学院理学系研究科 JSPS特別研究員)

Light hypothetical particles with masses up to O(100) MeV can be produced in the core of supernovae. Their subsequent decays to neutrinos can produce a flux component with higher energies than the standard flux. We study the impact of heavy neutral leptons, Z′ bosons, in particular U(1)Lμ−Lτ and U(1)B−L gauge bosons, and majorons coupled to neutrinos flavor-dependently. We obtain new strong limits on these particles from no events of high-energy SN 1987A neutrinos and their future sensitivities from observations of galactic supernova neutrinos.

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

EOS Dependence on Cooling of Isolated Neutron Stars

2024年12月20日(金) 14:00 - 15:15

Stavros Fakiolas (Ph.D. Student, University of Oxford, UK)

Neutron stars - the densest stars in the Universe - cool down mainly by loss of neutrinos, emitted from the stars' interior due to particle reactions. By comparing cooling models with observed surface temperature or luminosity, one can probe the properties of high-density matter, such as what kind of particles and states exist inside neutron stars. In this presentation, I will first review cooling theory, focusing on the neutrino cooling processes. In particular, we focus on the equation of state (EOS) uncertainties, which significantly affect cooling curves. We discuss aspects such as the effect of including hyperons in our EOS. Using the updated cooling code, C-HERES, we calculate cooling curves with different EOS. Finally, we present the future prospects for this study.

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

Applied plant genomics for evolutionary history, agriculture, and conservation

2024年12月19日(木) 16:00 - 17:00

アントニオ・エルナンデズ ロペズ (Professor, National Autonomous University of Mexico, Mexico)

I will explore the transformative role of genomic tools in understanding biological diversity across a range of organisms. By delving into the genetic blueprints of various species, we can unravel evolutionary histories, identify key traits for conservation, and develop strategies to preserve endangered ecosystems. Additionally, I will discuss practical applications of genomic data, such as enhancing agricultural biodiversity, improve traditional uses, and fostering sustainable development. Through case studies and recent advancements, this presentation highlights the critical intersection of genomics, biodiversity preservation, and its multifaceted uses in addressing global challenges.

会場: via Zoom

イベント公式言語: 英語

7th QGG Intensive Lectures: Emergence of space-time in matrix models

2024年12月17日(火) - 19日(木)

土屋 麻人 (静岡大学 教授)

Emergence of space-time is a key concept in matrix models as a nonperturbative formulation of string theory. In this lecture, starting with a brief introduction to nonperturbative effects in string theory, I will review various aspects of emergence of space-time in matrix models. The topics I discuss include dynamical triangulation, double scaling limit, eigenvalue instanton, large-N reduction, T-duality for D-brane effective theories (orbifolding), noncommutative geometry and covariant derivative interpretation. Finally, I will introduce the type IIB matrix model. (This is the 7th Intensive Lectures by Quantum Gravity Gatherings in iTHEMS. ) Program December 17 10.15~10.30 Registration and Coffee 10.30~12.00 Lecture 1 12.00~13.30 Lunch 13.30~15.00 Lecture 2 15.00~16.00 Coffee break 16.00~17.00 Lecture 3 17.30~19.30 Banquet December 18 10.15~11.45 Lecture 4 11.45~13.30 Lunch 13.30~15.00 Lecture 5 15.00~16.00 Coffee break 16.00~17.00 Lecture 6 December 19 10.15~11.45 Lecture 7 11.45~13.30 Lunch 13.30~15.00 Lecture 8 15.00~16.00 Coffee break 16.00~17.00 Lecture 9

会場: 研究本館 4階 435-437号室

イベント公式言語: 英語

Hopfions in Condensed Matter and Field Theory

2024年12月16日(月) 16:00 - 17:30

Avadh Saxena (Professor, Los Alamos National Laboratory, USA)

Abstract: Nontrivial topological defects such as knotted solitons called hopfions have been observed in a variety of materials including chiral magnets, nematic liquid crystals and even in ferroelectrics as well as studied in other physical contexts such as Bose-Einstein condensates. These topological entities can be modeled using the relevant physical variable, e.g., magnetization, polarization or the director field. Specifically, we find exact static soliton solutions for the unit spin vector field of an inhomogeneous, anisotropic three-dimensional (3D) Heisenberg ferromagnet and calculate the corresponding Hopf invariant H analytically and obtain an integer, demonstrating that these solitons are indeed hopfions [1]. H is a product of two integers, the first being the usual winding number of a skyrmion in two dimensions, while the second encodes the periodicity in the third dimension. We also study the underlying geometry of H, by mapping the 3D unit vector field to tangent vectors of three appropriately defined space curves. Our analysis shows that a certain intrinsic twist is necessary to yield a nontrivial topological invariant: linking number [2]. Finally, we focus on the formation energy of hopfions to study their properties for potential applications. Short bio: Avadh Saxena is former Group Leader of the Condensed Matter and Complex Systems group (T-4) at Los Alamos National Lab, New Mexico, USA where he has been since 1990. He is also an affiliate of the Center for Nonlinear Studies at Los Alamos. His main research interests include phase transitions, optical, electronic, vibrational, transport and magnetic properties of functional materials, device physics, soft condensed matter, non-Hermitian quantum mechanics, geometry, topology and nonlinear phenomena & materials harboring topological defects such as solitons, polarons, excitons, breathers, skyrmions and hopfions. He recently completed a book on “Phase Transitions from a Materials Perspective” (Cambridge University Press, 2024). He is an Affiliate Professor at the Royal Institute of Technology (KTH), Stockholm, Sweden and holds adjunct professor positions at the University of Barcelona, Spain, University of Crete, Greece, Virginia Tech and the University of Arizona, Tucson. He is Scientific Advisor to National Institute for Materials Science (NIMS), Tsukuba, Japan. He is a Fellow of Los Alamos National Lab, a Fellow of the American Physical Society (APS), a Fellow of the Japan Society for the Promotion of Science (JSPS) and a member of the Sigma Xi Scientific Research Society, APS and American Ceramic Society (ACerS).

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

Matter-Wave Interferometry in the Limit of High Mass and Internal Complexity, and the Relevance of Optomechanical Sources

2024年12月16日(月) 10:00 - 11:00

Markus Arndt (Professor, University of Vienna, Austria)

The seminar will feature a lecture by Professor Markus Arndt from the University of Vienna. Following the lecture, starting at approximately 11:00 AM, Nobuyuki Matsumoto will give a brief introduction to his research and conduct a tour of his laboratory. Hosted by Gakushuin University Co-hosted by iTHEMS

会場: 学習院大学 南4号館 007号室

イベント公式言語: 英語

Perturbative unitarity of Higgs inflation in the Riemannian and generalized geometry

2024年12月13日(金) 16:00 - 17:30

三倉 祐輔 (名古屋大学 高等研究院理学研究科C研 博士課程)

In a simple Higgs inflation model in metric-affine gravity, it is known that its UV cutoff is much smaller than the Planck scale. While it calls for UV completion, a concrete example has not yet been found, even with the large-N limit known as a successful technique to complete an original Higgs inflation defined on the Riemannian geometry. In this talk, after a review of the unitarity issue and previous attempts to complete Higgs inflation models, we investigate how small deformation of the simple Higgs inflation affects the emergence and properties of dynamical fields particularly in the large-N limit.

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

Particle acceleration in relativistic astrophysical plasmas

2024年12月13日(金) 14:00 - 15:15

カミリア・デミデム (理化学研究所 数理創造プログラム (iTHEMS) 研究員)

Relativistic astrophysical objects often display evidence of very efficient particle acceleration, such as X-ray and gamma-ray nonthermal emission and are widely recognized as potential sources of cosmic rays. Elucidating the physical mechanisms that turn these environments into such formidable particle accelerators is a longstanding problem of high-energy astrophysics. In this talk, I will briefly explain why shocks and turbulence, naturally expected to occur in these environments, could play an essential role in the acceleration of particles. I will then discuss some of the challenges that poses the description of these nonlinear processes, especially in the context of high-energy astrophysical sources, which involve astronomical ranges of scales and physical conditions much more extreme than we can probe in our laboratories or in the Solar system. Finally, I will share some recent results from my simulations.

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

Recent Advances in the Spectral Geometry of Domains and Approaches with Computer-Assisted Proofs

2024年12月12日(木) 15:00 - 17:00

遠藤 凌輝 (新潟大学 大学院自然科学研究科 数理物質科学専攻 博士課程)

What can we determine about the shape of a drum from its sound?"—This inverse problem has given rise to spectral geometry and has attracted researchers for over 110 years. The first half of the talk explains recent advances in shape optimization problems for domains with respect to eigenvalues of the Laplacian and the inverse problem known as "hearing the shape of a drum," presented in an accessible manner for experts from other disciplines. The second half introduces verified computation methods for eigenvalues, eigenfunctions, and shape derivatives. As applications, it presents newly established computer-assisted proofs for the minimization problem of eigenvalues with non-homogeneous Neumann boundary conditions, and the conjecture on the simplicity of the second Dirichlet eigenvalues for non-equilateral triangles.

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

Mechanism for Converting Temporal Rhythms into Spatial Patterns of Body Segment

2024年12月12日(木) 13:00 - 14:00

瓜生 耕一郎 (東京科学大学 生命理工学院 准教授)

In development, spatially periodic structures are spontaneously formed in various tissues. These developmental structures are also formed in a proper temporal order. How is such spatial and temporal coordination achieved in morphogenesis? In this presentation, we discuss the mechanism that translates temporal rhythms of gene expression into spatially periodic patterns in vertebrate body segment formation. Mechanisms for converting oscillatory signals into vertebrate body segments have been proposed previously. Cooke and Zeeman 1976 proposed the Clock and Wavefront model based on the concept of the catastrophe theory. Still, it remains unclear how this conceptual model actually works in embryos. Here we develop a mathematical model aided by recent imaging and molecular genetics data and reveal a spatiotemporal bifurcation structure for vertebrate segment formation by using the dynamical systems theory.

会場: セミナー室 (359号室) / via Zoom

イベント公式言語: 英語

Studying quark-gluon plasma with multi-stage dynamical models in relativistic nuclear collisions

2024年12月10日(火) 15:30 - 17:00

金久保 優花 (理化学研究所 数理創造プログラム (iTHEMS) 特別研究員)

A collision of relativistically accelerated large nuclei creates the hottest matter on Earth — quark-gluon plasma (QGP). The properties of QGP have been studied through comparisons of final-state particle distributions between theoretical models and experimental data. To quantitatively constrain QGP properties, it is necessary to build Monte Carlo models that simulate the space-time evolution of the system throughout the entire collision process. This includes the initial matter production from the accelerated nuclei, the evolution of QGP, hadronisation, and the evolution of hadron gas. In this talk, I will first explain how theoretical models, based on relativistic hydrodynamics and hadronic transport, are conventionally built and how they successfully extract QGP properties. Next, I will discuss a hot topic: the possibility of finding QGP in proton-proton collisions, based on results from a state-of-the-art model that includes both equilibrated and non-equilibrated systems. Also, I will introduce a novel Monte Carlo initial state model based on perturbative QCD minijet production supplemented with a saturation picture. This Monte-Carlo EKRT model is one of the first initial state models for hydrodynamics to describe initial particle production from small to large momentum within a single framework, where total energy-momentum and charge conservations are imposed.

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

Entanglement of astrophysical neutrinos

2024年12月10日(火) 13:30 - 15:00

Baha Balantekin (Eugene P. Wigner Professor, Department of Physics, University of Wisconsin-Madison, USA)

Collective oscillations of neutrinos represent emergent nonlinear flavor evolution phenomena instigated by neutrino-neutrino interactions in astrophysical environments with sufficiently high neutrino densities. In this talk, after a brief introduction, it will be shown that neutrinos exhibit interesting entanglement behavior in simplified models of those oscillations. Attempts to study this behavior using classical and quantum computers will be described. An intriguing connection to the heavy-element nucleosynthesis, namely the possibility of neutrino entanglement driving a new kind of i-process nucleosynthesis, will be introduced,

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

Dark matter from inflationary quantum fluctuations

2024年12月9日(月) 14:00 - 15:30

Mohammad Ali Gorji (Junior Faculty, Center for Theoretical Physics of the Universe, Institute for Basic Science, Republic of Korea)

We explore a scenario in which dark matter is a massive bosonic field, arising solely from quantum fluctuations generated during inflation. In this framework, dark matter exhibits primordial isocurvature perturbations with an amplitude of O(1) at small scales that are beyond the reach of current observations, such as those from the CMB and large-scale structure. Assuming a monochromatic initial power spectrum, we identify the viable parameter space defined by dark matter mass and the length scale of perturbations. A key prediction of this scenario is copious formation of subsolar dark matter halos at high redshifts.

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

The second internal meeting of RIKEN Quantum

2024年12月6日(金) 16:00 - 19:30

Program: 16:00-16:05 Opening remarks --- Shinichiro Fujii (TRIP / iTHEMS) 16:05-16:35 Tensor network simulations of lattice gauge theory --- Yantao Wu (iTHEMS) 16:35-17:05 Quantum electrodynamics meets quantum chemistry: Theoretical foundations for polariton dynamics and control --- Himadri Pathak (iTHEMS / R-CCS) 17:05-17:35 Towards quantum advantage: imaginary Hamiltonian variational ansatz on the Schwinger model and the MaxCut problem --- Xiaoyang Wang (iTHEMS / R-CCS) 17:35-17:59 Researchers conducting collaborative research proposals (TRIP) --- 3 min.*8       Takaaki Kuwahara (Kyoto Univ.)       Maxime Medevielle (Univ. of Tokyo)       Tanay Pathak (Kyoto Univ.)       Koudai Sugimoto (Keio Univ.)       Takayuki Suzuki (NICT)       Hidetoshi Taya (Keio Univ.)       Takahiro Terada (Nagoya Univ.)       Tianchun Wang (Keio Univ.) 17:59-18:00 Closing remarks --- Seiji Yunoki (CPR / R-CCS / RQC) 18:10-19:30 Banquet at Cafeteria 1, Welfare and Conference Bldg (C61) 1F, RIKEN, Wako

会場: セミナー室 (359号室)

イベント公式言語: 英語

Bacterial ecospecies and ecoclines

2024年12月5日(木) 16:00 - 17:00

Daniel Falush (Professor, Shanghai Institute of Immunity and Infection, Chinese Academy of Sciences, China)

All bacteria reproduce clonally but some species exchange DNA frequently enough that they have well mixed geographic gene pools, similar to those found in outbreeding animals and plants. Using data from multiple species we show that these “recombinogenic” bacteria also have genome-wide genetic structures generated by natural selection, including discrete “ecospecies” and continuous “ecoclines”. These structures reflect evolutionary strategies employed within natural populations, which can be dissected using the powerful techniques of molecular microbiology, providing a unique new view into the private lives of bacteria.

会場: via Zoom / セミナー室 (359号室)

イベント公式言語: 英語