Workshop

RIKEN–Berkeley Workshop on Quantum Gravity 2025

October 23 (Thu) - 24 (Fri) 2025

This workshop will serve as the first meeting of the collaboration between the Leinweber Institute for Theoretical Physics (LITP) at the University of California Berkeley and the RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS). Participation is open and researchers from other institutions are welcome to attend. The workshop will feature talks on recent developments in the field of Quantum Gravity and other relevant topics.

Venue: via Zoom / #359 (23rd Morning) & #435-437 (23rd Afternoon & 24th Morning), Main Research Building

Event Official Language: English

Japan-UK Workshop on Quantum Gravity

September 22 (Mon) - 26 (Fri) 2025

The universe at extremely early times is expected to be described by some theory of quantum gravity, although we still do not know precisely what quantum gravity actually is. In modern approaches to quantum gravity, the path integral point of view provides a fundamental framework towards answering this pressing question. However, an evaluation or even just a precise definition of the path-integral for a full-fledged quantum gravity is one of the most important open problems in modern theoretical physics.

Venue: 8F, Integrated Innovation Building (IIB)

Event Official Language: English

Functional Renormalization Group at RIKEN 2025

August 25 (Mon) - 26 (Tue) 2025

Functional Renormalization Group (FRG) is a powerful theoretical framework for investigating physical systems described by field theory. Its applications span a wide range of areas, from condensed matter and statistical physics to particle physics and gravity. This two-day workshop aims to provide an overview of recent applications and developments of FRG across various fields, foster discussions on future directions, and explore opportunities for new collaborations.

Venue: #345-347, Main Research Building, RIKEN Wako Campus

Event Official Language: English

iTHEMS-NCTS Workshop

August 18 (Mon) - 21 (Thu) 2025

This workshop aims to strengthen collaboration between researchers at RIKEN iTHEMS and the National Center for Theoretical Sciences in Taiwan. It will be a four-day event, with the first two days dedicated to interdisciplinary topics. The last two days will focus on specialized areas, with one day devoted to condensed matter physics and the other to high-energy physics, including quantum gravity.

Venue: via Zoom / RIKEN Wako Campus

Event Official Language: English

Crossroads of Virology and Mathematical Sciences

August 8 (Fri) 9:30 - 17:30, 2025

Makoto Takeda (Professor, Graduate School of Medicine, The University of Tokyo)
Yasuyuki Yamaji (Professor, Graduate School of Agricultural and Life Sciences, The University of Tokyo)
Kotaro Kiga (Director, Japan Institute for Helth Security)
Daishi Fujita (Associate Professor, Kyoto University Institute for Advanced Study (KUIAS))
Miyuki Koiso (Professor Emeritus, Kyushu University)
Daisuke Kuroda (Associate Professor, Department of Biosciences, College of Humanities and Sciences, Nihon University)
Catherine Beauchemin (Deputy Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Shinichi Tanigawa (Associate Professor, Graduate School of Information Science and Technology, The University of Tokyo)
Takao Hashiguchi (Professor, Institute for Life And Medical Sciences, Kyoto University)
Hideo Fukuhara (Associate Professor, International Institute for Zoonosis Control, Hokkaido University)
Shohei Kojima (Special Postdoctoral Researcher, Genome Immunobiology RIKEN Hakubi Research Team, RIKEN Center for Integrative Medical Sciences (IMS))
Shuhei Miyashita (Assistant Professor, Graduate School of Agricultural Science, Tohoku University)
Ryoko Oishi-Tomiyasu (Professor, Institute of Mathematics for Industry, Kyushu University)
Suzuki Yuta (Principal Investigator, Japan Science and Technology Agency (JST))
Adnan Sljoka (Research Scientist, Molecular Informatics Team, RIKEN Center for Advanced Intelligence Project (AIP))

By creating a shared space for dialogue, we aim to stimulate new research directions and foster collaborative insights through the integration of mathematical sciences into studies of both the structural principles that govern viral form and function, and the dynamics of viral replication. We invite participation from both mathematical and theoretical scientists interested in the structure and replication mechanisms of viruses, as well as virologists who are open to exploring the potential of mathematical abstraction. Program: Morning Session I (Viruses) 10:00–10:20 Measles virus engineering Makoto Takeda (The University of Tokyo, Graduate School of Medicine) 10:20–10:40 Plant immunity to potexviruses Yasuyuki Yamaji (The University of Tokyo, Graduate School of Agricultural and Life Sciences) 10:40–11:00 Sophisticated phage infection strategies and bacterial defense responses Kotaro Kiga (National Institute of Infectious Diseases) Break (11:00–11:15) Morning Session II (Molecules, Math) 11:15–11:35 Designing Polyhedral Molecular Architectures at Will Daishi Fujita (Kyoto University, Institute for Advanced Study) 11:35–11:55 Anisotropic energy and (curved) polyhedron Miyuki Koiso (Kyushu University) 11:55–12:15 Nature-Inspired Design of Two-Component Protein Assemblies: From Cytoskeleton-Like to Virus-Like Structures Yuta Suzuki (JST PRESTO) Lunch Break (12:15–13:20) Afternoon Session I (Comp Sci, Math) 13:20–13:40 Computer-aided antibody design Daisuke Kuroda (Nihon University, Department of Life Sciences) 13:40–14:00 Revealing Protein Allostery and Functional Dynamics via Rigidity Theory and NMR Adnan Sljoka（RIKEN AIP） 14:00–14:20 Using mathematical models to identify experimental pitfalls when probing virus replication in vitro Catherine Beauchemin (RIKEN iTHEMS) 14:20–14:40 Combinatorics behind statics and flexibility of graphs Shinichi Tanigawa (The University of Tokyo, Graduate School of Information Science and Technology) Break (14:40–14:55) Afternoon Session II (Structures) 14:55–15:15 Glycoprotein structures in human pathogenic RNA viruses Takao Hashiguchi (Kyoto University, Graduate School of Medicine and Biomedical Sciences) 15:15–15:35 Introduction of cryo-electron microscopy facilities at Hokkaido University Hideo Fukuhara (Hokkaido University, Research Center for Zoonosis Control) Break (15:35–15:50) Afternoon Session III (Viruses, Math) 15:50–16:10 Human genetics during virus infection Shohei Kojima (Keio University, Bio2Q) 16:10–16:30 Suicidal population resistance of land plants against viruses Shuhei Miyashita (Tohoku University, Graduate School of Agricultural Science) 16:30–16:50 Mathematical and crystallographic perspectives in virology Ryoko Tomiyasu (Kyushu University, IMI) Organizers: Catherine Beauchemin (RIKEN iTHEMS) Makoto Takeda (University of Tokyo, Graduate School of Medicine) Ryoko Tomiyasu (Kyushu University, IMI)

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

The Theory of Periodic Tangles & Their Interdisciplinary Applications

July 28 (Mon) - August 1 (Fri) 2025

The mathematical characterization of entanglement holds immense potential for describing the mechanical functions of diverse physical systems and materials. A universal interdisciplinary study, involving scientists, engineers, and artists promises both advance of the field itself and significant contribution to the research and design of innovative solutions for textiles, medical devices, polymers, molecular chemistry, or construction materials among others. The program seeks an alternative to the trial–and–error approach, bringing together academia and industry to seek new sustainable solutions and inspiration, contributing to society. It will consist not only of scientific exchanges but will promote cultural impact by organizing exhibitions or hands–on workshops. Additionally, it will encourage several discussions by providing networking opportunities and utilizing the unique venue of House of Creativity at Tohoku University. This workshop will gather researchers from various disciplines and include invited lectures, a poster session, roundtable discussions, and brainstorming activities. Our focus will be on exploring the connections between knot theory and its applications in areas such as polymers and soft matter, textile mechanics, graphic design, and more. This event includes a joint symposium between the WPI–AIMR (Tohoku University) and WPI–SKCM2 (Hiroshima University) on Friday, August 1st, 2025: INTERWOVEN: A WPI–AIMR & WPI–SKCM2 Symposium, Towards a Universal Topological Model of Entangled Structures for Sustainable Metamaterials Please fill in the registration form by June 16th 2025. Confirmed speakers (alphabetical order): Jörn Dunkel (Massachusetts Institute of Technology) Yuanyuan Guo (Tohoku University) Tatsuki Hayama (Keio University) Louis H. Kauffman (University of Illinois at Chicago) Yuka Kotorii (Hiroshima University) Sofia Lambropoulou (National Technical University of Athens) Eleni Panagiotou (Arizona State University) Pedro M. Reis (École Polytechnique Fédérale de Lausanne) Takahiro Sakaue (Aoyama Gakuin University) Vanessa Sanchez (Rice University) Henry Segerman (Oklahoma State University) Koya Shimokawa (Ochanomizu University) Hiroshi Suito (Tohoku University) Ryuichi Tarumi (Osaka University) Hirofumi Wada (Ritsumeikan University) Please refer to the workshop website via the relevant link for more details. We are looking forward to your participation and to welcoming you to Sendai!

Venue: TOKYO ELECTRON House of Creativity, Katahira Campus, Tohoku University

Event Official Language: English

Recent Developments and Challenges in Tensor Networks: Algorithms, Applications to science, and Rigorous theories

July 28 (Mon) - August 8 (Fri) 2025

Venue: Panasonic Hall, Yukawa Institute for Theoretical Physics, Kyoto University

Event Official Language: English

iTHEMS-TheoryCenter(KEK) Scientific Writing and DEI Workshop

June 24 (Tue) - 25 (Wed) 2025

Ashleigh Griffin (Professor, Department of Biology, University of Oxford, UK)
Stuart West (Professor, Department of Biology, University of Oxford, UK)
Ryosuke Iritani (Senior Research Scientist, Division of Fundamental Mathematical Science, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))

This is a two-day KEK-iTHEMS workshop on scientific writing and diversity, equity, and inclusion. For more details, please visit the workshop website via the relevant link.

Venue: 2F Large Conference Room, Administrative Headquarters, RIKEN Wako Campus

Event Official Language: English

Mini-Workshop on Neuro Science

May 16 (Fri) 9:00 - 12:00, 2025

Satoshi Iso (Director, RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS))
Takuya Isomura (Unit Leader, Brain Intelligence Theory Unit, RIKEN Center for Brain Science (CBS))
Taro Toyoizumi (Team Director, Laboratory for Neural Computation and Adaptation, RIKEN Center for Brain Science (CBS))
Kazuo Okanoya (Professor, Advanced Comprehensive Research Organization (ACRO), Teikyo University)
Atsushi Iriki (Specially Appointed Professor, Advanced Comprehensive Research Organization, Teikyo University)
Gary Shiu (Professor, Department of Physics, University of Wisconsin-Madison, USA)

[Program] 9:00am – 9:05am Satoshi Iso (iTHEMS RIKEN) “Opening Remarks” 9:05am – 9:35am Takuya Isomura (CBS RIKEN) “Triple equivalence integrates neural network dynamics, statistical inference, and computation” 9:45m – 10:15am Taro Toyoizumi (CBS RIKEN) “Chaotic neural dynamics facilitate probabilistic computations through sampling” 10:25am – 10:55am Kazuo Okanoya (Teikyo University) “Brain topography and auditory processing in birds and rats” 11:05am – 11:30am Atsushi Iriki (Teikyo University, iTHEMS RIKEN) “From Classical to Quantum: Rethinking Science, Consciousness, and Civilization” 11:30am – Gary Shiu (University of Wisconsin) “Summary: Mathematical Science and Brain” Followed by a seminar 2:00pm – 3:30pm Prof. Gary Shiu (University of Wisconsin) Topology and Brain Science Room 359, 3rd floor, Main Research Building, RIKEN

Venue: #345-347, Main Research Building, RIKEN Wako Campus (Main Venue) / via Zoom

Event Official Language: English

From Quarks to Neutron Stars: Insights from kHz gravitational waves

April 23 (Wed) - 24 (Thu) 2025

Astronomical observations of binary neutron star mergers and supernovae provide unique opportunities to explore physics spanning from quarks to neutron stars. The groundbreaking multi-messenger observation of GW170817, combining electromagnetic signals and gravitational waves, vividly demonstrated this potential. Furthermore, if a core-collapse supernova were to occur in our galaxy, it would likely become the first event where electromagnetic signals, neutrinos, and gravitational waves are detected together. The interior of neutron stars is not yet well understood due to their extreme density, where exotic states of matter may emerge. Gravitational waves, particularly in the kilohertz band, play a crucial role in extracting information about such ultra-high densities. In recent years, several concepts for kilohertz-band gravitational wave detectors, such as Australia's NEMO, have been proposed to advance multi-messenger studies of high density astrophysical objects. KAGRA in Japan is also exploring upgrades aimed at enhancing high-frequency sensitivity, which could significantly improve sky localization accuracy and enable the detection of post-merger signals. This workshop aims to explore the transformative potential of high-frequency gravitational wave observations for multi-messenger astrophysics, with a focus on their implications for nuclear and neutron star physics. The workshop aims to spark dynamic discussions and cultivate new collaborations among participants through invited talks by leading experts and engaging poster presentations.

Venue: via Zoom

Event Official Language: English

Third Workshop on Density Functional Theory: Fundamentals, Developments, and Applications (DFT2025)

March 25 (Tue) - 27 (Thu) 2025

The density functional theory (DFT) is one of the powerful methods to solve quantum many-body problems, which, in principle, gives the exact energy and density of the ground state. The accuracy of DFT is, in practice, determined by the accuracy of an energy density functional (EDF) since the exact EDF is still unknown. Currently, DFT has been used in many communities, including nuclear physics, quantum chemistry, and condensed matter physics, while the fundamental study of DFT, such as the first principle derivations of an accurate EDF and methods to calculate many observables from obtained densities and excited states, is still ongoing. However, there has been little opportunity to have interdisciplinary communication. On December 2022, we had the first workshop on this series (DFT2022) at Yukawa Institute for Theoretical Physics, Kyoto University, and several interdisciplinary discussions and collaborations were started. On February 2024, we had the second workshop on this series (DFT2024) at RIKEN Kobe Campus, and more stimulated discussion occured. To keep and extend collaborations, we organize the third workshop. Since the third workshop, we extend the scope of the workshop to the development and application of DFT as well. In this workshop, the current status and issues of each discipline will be shared towards solving these problems by meeting together among researchers in mathematics, nuclear physics, quantum chemistry, and condensed matter physics. This workshop mainly comprises lectures/seminars on cutting-edge topics and discussion, while sessions composed of contributed talks are also planned.

Venue: 8F, Integrated Innovation Building (IIB) / via Zoom

Event Official Language: English

Kyushu IAS-iTHEMS conference: Non-perturbative methods in QFT

March 10 (Mon) - 14 (Fri) 2025

The most commonly used approach in the study of QFT is perturbation theory. Indeed, we have succeeded in extracting various physical quantities from perturbative (asymptotic) expansions. However, some physical phenomena cannot be captured through perturbative analyses alone. How can we extract these non-perturbative effects? In QFTs with conformal symmetry (i.e., CFTs), correlation functions can be computed using a method called the conformal bootstrap. This non-perturbative method differs entirely from the usual correlation function analysis methods of QFT, as it does not even assume the existence of a Lagrangian. Through the use of the conformal bootstrap, we have actually made significant progress in the non-perturbative understanding of CFTs. Furthermore, according to the holographic principle, CFTs provide a non-perturbative formulation of QFTs with gravity (i.e., quantum gravity). By applying the holographic principle to various non-perturbative results from CFTs, such as those obtained from the conformal bootstrap, we have made remarkable advances in understanding the non-perturbative aspects of quantum gravity. Conversely, the holographic principle is also used to understand properties of QFTs that are difficult to analyze perturbatively, through gravity.

Venue: Kyushu University Ito Campus, Inamori Hall

Event Official Language: English

RIKEN-Nara Women's University Joint Diversity Promotion Workshop 2025

March 3 (Mon) - 4 (Tue) 2025

The RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) and the Faculty of Science at Nara Women's University are promoting a project to foster female researchers under the auspices of the RIKEN Diversity Promotion Office. As part of the program, 19 undergraduate and graduate students from Nara Women's University will visit several laboratories on the RIKEN Wako campus to ask questions about their research and hold workshops/presentations with iTHEMS researchers. Organizers: RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) Faculty of Science, Nara Women's University Program: 13:50-15:15 RIBF Facility, RIKEN Nishina Center (RNC) (E01, Nishina RIBF Building) 15:30-16:30 RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) (C01, Main Research Building, #359) Introduction to iTHEMS: Tetsuo Hatsuda (iTHEMS Director) Lecture and Q&A: Nagisa Hiroshima (iTHEMS) 16:45-18:00 RIKEN Center for Brain Science (CBS) (C56, Ikenohata Research Building, #316) Laboratory for Sensorimotor Integration (Fumi Kubo, Team Leader) 18:30-21:00 Networking Session (C01, Research Building 3F) 9:15-10:30 RIKEN Center for Advanced Photonics (RAP) (C32, Laser Research Building, Mid Conference Room A) Photonics Control Technology Team (Satoshi Wada, Team Leader) 10:45-12:00 RIKEN Center for Sustainable Resource Science (CSRS) (S01, Biological Science Research Building, S311) Molecular Bioregulation Research Team (Shinya Hagihara, Team Leader)

Venue: RIKEN Wako Campus

Asymptotics in astrophysics iTHEMS workshop

February 25 (Tue) - 28 (Fri) 2025

This workshop will include overview talks of application of asymptotics and perturbation theory techniques in (wave transport or oscillation related) astrophysics and cosmology eigenvalue problems. In addition, there will be introductory talks about fundamental asymptotics and perturbation theory techniques used in theoretical physics. The purpose of this interdisciplinary workshop is to identify problems in astrophysics and related fields including, but not limited to, stellar structure and evolution, black holes and high-energy physics which can be solved using existing asymptotics and perturbation theory methods in theoretical physics problems (e.g. quantum field theory, gravity), and vice versa.

Venue: 8F, Integrated Innovation Building (IIB)

Event Official Language: English

Theories of Astrophysical Big Bangs 2025

February 17 (Mon) - 19 (Wed) 2025

We are pleased to announce an international workshop on theories of Astrophysical Big Bangs. The main topics of the workshop are listed below, although the topics are not limited to these areas. We aim to cover a broad range of astrophysical research concerning various types of cosmic explosions and compact objects. Neutron Stars Neutron Star Mergers Gravitational Waves Gamma-Ray Bursts Supernovae Supernova Remnants This workshop aims to assemble leading experts in various fields of astrophysical big bangs for vibrant discussions and to foster new collaborations among participants. Program (last updated 2025.02.17) 17Feb. 10:00-10:10 Opening Remarks by Hiro Nagataki (RIKEN) Special Talk 10:10-11:10 (50+10) Daniel Kasen (U.C. Berkeley) Radiative Transfer Modeling of Explosive Transients NS mergers, Kilonovae, and Gravitational Waves 11:10-11:50 (30+10) Masaomi Tanaka (Tohoku U.) Decoding light curves and spectra of kilonovae 11:50-12:30 (30+10) Kenta Hotokezaka (U. Tokyo) Kilonova Nebular Emission 12:30-14:00 Lunch Break and Poster Session 14:00-14:40 (30+10) Kipp Cannon (U. Tokyo) Selection Effects in Gravitational-Wave Observations 14:40-15:20 (30+10) Koutarou Kyutoku (Chiba U.) Signature of hadron-quark crossover in binary-neutron-star mergers 15:20-15:50 Poster Presentations & Coffee Break 15:50-16:30 (30+10) Luca Baiotti (Osaka U.) Investigating ultra-high-density equations of state through gravitational waves from binary neutron stars mergers Supernovae & Gamma-Ray Bursts (Chair A. Mizuta) 16:30-17:10 (30+10) Nozomu Tominaga (NAOJ) Transient studies using Subaru/Hyper Suprime-Cam 17:10-17:50 (30+10) Tianshu Wang (UCB) Three-Dimensional Long-Term CCSN Simulations: New Insights and Challenges 18 Feb. Gamma-Ray Bursts 9:00-9:30 (25+5) Akira Mizuta (RIKEN) 3D relativistic GRB jet propagation in collapsars 9:30-10:00 (25+5) Jin Matsumoto (Fukuoka U.) Nonlinear dynamics of relativistic magnetized jet with field reversals 10:00-10:30 (25+5) Hirotaka Ito (RIKEN) Numerical simulations of photospheric emission in GRBs 10:30-11:00 (25+5) Maria Dainotti (NAOJ) GRBs and SNe Ia cosmology to cast the Hubble constant tension 11:00-11:30 Poster Presentations & Coffee Break 11:30-12:10 (30+10) Kunihito Ioka (Kyoto U.) GRB Cocoon + Scattering in FRB Neutron Stars 12:10-12:40 (25+5) Hajime Sotani (Kochi U.) Supernova gravitational waves and asteroseismology 12:40-14:00 Lunch Break & Poster Presentations 14:00-14:30 (25+5) Akira Dohi (RIKEN) Modeling of Clocked X-ray Bursters Progenitor Stars 14:30-15:10 (30+10) Hideyuki Umeda (U. Tokyo) Progenitors of low-mass Fe core collapse supernovae and properties of supernova explosions 15:10-15:40 (25+5) Lucy McNeill (Kyoto U.) Finite temperature treatment of white dwarf merger progenitors 15:40-16:10 Poster Presentations & Coffee Break Core-Collapse Supernovae 16:10-16:50 (30+10) Tomoya Takiwaki (NAOJ) Diversity of explosion mechanisms of core-collapse supernovae 16:50-17:30 (30+10) Hiroki Nagakura (NAOJ) Open issues in numerical modeling of core-collapse supernova 17:30-18:10 (30+10) Yudai Suwa (U. Tokyo) Probing supernova interiors with neutrinos 18:30-21:00 Banquet & Poster Presentations 19 Feb. Supernovae, Supernova Remnants, and Nucleosynthesis 10:00-10:40 (30+10) Ke-Jung Chen (ASIAA) Supernovae of very massive stars 10:40-11:20 (30+10) Masaomi Ono (ASIAA) Evolution of core-collapse supernovae from explosion to supernova remnant 11:20-12:00 (30+10) Hiroya Yamaguchi (JAXA) XRISM view of supernova remnants 12:00-12:40 (30+10) Shiu-Hang Lee (Kyoto U.) Super high-speed three-dimensional hydrodynamic simulations of supernova remnants and their applications in the era of microcalorimetric X-ray spectroscopy 12:40-14:00 Lunch Break 14:00-14:40 (30+10) Gilles Ferrand (U. Manitoba) Typing thermonuclear explosions from observations of young supernova remnants 14:40-15:20 (30+10) Nobuya Nishimura (U. Tokyo) Toward new nuclear astrophysics experiments for explosive nucleosynthesis in core-collapse supernovae 15:20-16:00 (30+10) Ryosuke Hirai (RIKEN) Supernovae in binary systems 16:00-17:00 (60) Coffee Break and Free Discussion

Venue: Conference room in Administrative Headquarters (2nd Floor, Feb. 17 and 18) Okochi Hall (Feb.19), RIKEN Wako Campus

Event Official Language: English

Pebbles in Planet Formation

February 10 (Mon) - 13 (Thu) 2025

Research on planet formation involves various approaches, including explorations of small solar system bodies, observations of protoplanetary disks, dust experiments, simulations, and theoretical studies. One of the primary objectives in this field is to develop a comprehensive theory that explains how kilometer-sized planetesimals form from micrometer-sized dust grains, drawing upon findings from these diverse research methods. This workshop will focus on the concept of pebbles, which play a crucial role in the planet formation process. Pebbles — typically defined as solids ranging from millimeter to centimeter in size — are intermediate building blocks in planet formation, though their definition varies depending on the context. Assuming pebbles has led to theoretical advances in mechanisms such as streaming instability and pebble accretion, which promote the formation and growth of planetesimals. Additionally, pebbles have been linked to barriers against dust growth, such as the bouncing barrier. Furthermore, observations of protoplanetary disks have revealed the size distribution and porosity of solids, while the strength and thermal conductivity of comets obtained by the Rosetta mission suggest the accumulation of pebbles due to disk instabilities. However, inconsistencies have been pointed out between pebble formation and theories of dust growth. This workshop aims to revisit and refine our understanding of solid materials implicated in planet formation, particularly in light of findings from solar system explorations and protoplanetary disk observations. We aim to reevaluate the definition and role of pebbles in the broader context of planet formation, with a special focus on the current challenges and open questions in the field. The workshop will include discussions of experiments and simulations of dust growth and collisions, and planetesimal formation mechanisms such as streaming instability. The workshop features keynote talks from the perspectives of explorations, observations, experiments, simulations, and theories, and we also call for presentations on related topics.

Venue: National Astronomical Observatory of Japan (Mitaka Campus) (Main Venue) / via Zoom

Event Official Language: English

High Energy Physics in the Quantum Era

December 2 (Mon) - 4 (Wed) 2024

This workshop is co-hosted by KEK Theory Center and RIKEN iTHEMS to inaugurate their new partnership in theoretical studies of high energy physics and related subjects with special emphasis on development and application of quantum technologies. The workshop aims for developing new connection between particle physics and quantum information/technologies. In the situation where significant progress is expected in the field of quantum information and technologies, it is quite important to discuss how such progress can be used in physics researches. Also, new techniques or new theoretical formulations of quantum field theory/quantum gravity may give deeper understanding of our quantum world. In this workshop, we would like to have world-leading researchers both from particle physics and quantum technologies, and drive lively discussions on future prospects. We are trying to limit the number of talks to be as minimal as possible, so that we have plenty of time for discussions. The workshop is in-person only.

Venue: Kobayashi Hall, KEK Tsukuba Campus

Event Official Language: English

Entanglements & Applications

November 18 (Mon) 9:30 - 15:00, 2024

Myfanwy Evans (Professor, Institute of Mathematics, University of Potsdam, Germany)
Stephen Hyde (Emeritus Professor, Materials Physics, Australian National University, Australia)
Toky Andriamanalina (Ph.D. Student, Institute of Mathematics, University of Potsdam, Germany)

9:30-10:30: Toky Andriamanalina Title: Untangling 3-periodic entanglements of filaments and nets Abstract: Entanglements of curves and nets can used to describe various biological and chemical structures, such as coordination polymers, liquid crystals, or DNA origami crystals. We recently developed new diagrammatic descriptions of 3-periodic entanglements. These new diagrams are drawn out of a projection along one axis of a unit cell of a 3-periodic structure. By using these diagrams, we define the notion of untangling number for 3-periodic structures, which is a measure of complexity of the entanglement. Thanks to this, it is now possible to characterise the least tangled structures that we call ground states, and in particular we show that the rod packings are the generic ground states of entanglements of curves. 10:30-11:00: coffee break 11:00 - 12:00: Stephen Hyde Title: Tangles... and untangles Abstract: Knots, braids, links, self-entangled nets, multiple catenated infinite nets... are examples of what we call, simply, “tangles”. They are relevant to molecular-scale (bio)materials, from duplexed ssRNA to metal-organic frameworks. We are interested in understanding: 1.Which tangles are “simple”? 2.How tangled is a tangle!? Our tangle toolkit is a simple one: we assemble helices into networks, allowing a broad spectrum of tangles to be built, from knots to tangled nets. Interesting “simple” tangles are entanglements of the edges of Platonic polyhedra [1] and entangled 2-periodic nets [2]. A proposed answer to point 2. above will be discussed. if there is time. The ideas are at present largely unpublished, and being working into a book to be published, we hope, in late 2025 [3]. 13:00 - 14:00: Myfanwy Evans Title: Can solvents tie knots? Helical folds of biopolymers in liquid environments. Abstract: Using a simulation technique based on the morphometric approach to solvation, we performed computer experiments which fold a short open flexible tube, modelling a biopolymer in aqueous environments, according to the interaction of the tube with the solvent alone. We find an array of helical geometries that self-assemble depending on the solvent conditions, including symmetric double helices where the strand folds back on itself and overhand knot motifs. Interestingly these shapes—in all their variety—are energetically favoured over the optimal helix. By differentiating the role of solvation in self–assembly our study helps illuminate the energetic background scenery in which all soluble biomolecules live. This event is organized with the Interdisciplinary Math Study Group.

Venue: Seminar Room #359

Event Official Language: English

iTHEMS Science Outreach Workshop 2024

November 15 (Fri) - 17 (Sun) 2024

This year's meeting on "Outreach of RIKEN iTHEMS 2024@Sendai&Zoom" will be held from FRI November 15 to SUN November 17, as a face-to-face meeting at TOKYO ELECTRON House of Creativity of Tohoku Forum for Creativity in cooperation with iTHEMS SUURI-COOL (Sendai) using ZOOM for the necessary part as well.

Venue: TOKYO ELECTRON House of Creativity, Katahira Campus, Tohoku University (Main Venue) / via Zoom

Event Official Language: Japanese

Knitting Day

November 1 (Fri) 10:00 - 16:00, 2024

Tomohiko Sano (Senior Assistant Professor, Department of Mechanical Engineering, Faculty of Science and Technology, Keio University)
Samuel Poincloux (Assistant Professor, Department of Physics and Mathematics, College of Science and Engineering, Aoyama Gakuin University)
Taiki Goto (Master's Student, Keio University)
Daisuke S. Shimamoto (Master's Student, The University of Tokyo)
Kotone Tajiri (Master's Student, Keio University)
Sonia Mahmoudi (Assistant Professor, Mathematical Science Group, Advanced Institute for Materials Research (AIMR), Tohoku University)

The 'Knitting Day' event is a one-day gathering that brings together students and researchers from diverse fields to explore the fascinating connections between the topology and mechanics of knitting. It aims to foster interdisciplinary discussions on how knitting techniques can be understood through mathematical, physical, and engineering lenses and their potential applications in industry. This event is organized with the Interdisciplinary Math Study Group. Schedule: 10:00 – 10:30: Welcome coffee 10:30 – 11:00: Samuel Poincloux 11:10 – 11:30: Kotone Tajiri 11:30 – 12:00: Discussion 12:00 – 13:00: Lunch 13:00 – 13:30: Daisuke Shimamoto 13:40 – 14:00: Taiki Goto 14:00 – 14:30: Discussion 14:30 – 15:10: Sonia Mahmoudi 15:10 – 16:00: Discussion & Coffee Break 16:00-18:00: Internal Discussion From 18:00: Dinner Titles: Taiki Goto: Twist deformation in trefoil knot Sonia Mahmoudi: A new topological model of knitting Samuel Poincloux: Knit mechanics and frictional troubles Daisuke Shimamoto: TBA Kotone Tajiri: Curling morphology of knitted fabrics: structure and mechanics

Venue: #345-347, 3F, Main Research Building

Event Official Language: English