This April, iTHEMS entered a new phase with a renewed and expanded structure.
While we continue to grow and evolve, the spirit of iTHEMS remains unchanged.

That spirit is grounded in three core pillars:

• A place where young researchers can freely and deeply pursue their own interests.
• A place where scientists from diverse fields meet, talk, and discover new perspectives together.
• A place that not only helps young researchers launch their careers globally, but also draws top-level talent from around the world.

These values remain central as we move forward — and this year, we are especially pleased to welcome several new research teams from applied and interdisciplinary fields as part of our expanded structure. Each team brings unique strengths, expertise, and questions. We are excited to collaborate, to learn from each other, and to build together as one iTHEMS.

In this environment, where people from different backgrounds bring their own questions to the table, something special happens. Ideas resonate, combine, and sometimes spark entirely new areas of science. That’s the kind of exciting, creative energy we strive to cultivate at iTHEMS.

Most of all, we want iTHEMS to be a place where young researchers can truly enjoy their research and thrive.

We’re truly excited to continue growing together with all of you, researchers, collaborators, and supporters alike. Working hand in hand with universities, research institutions, and partners in policy and science support both in Japan and abroad,
iTHEMS will continue to evolve with both flexibility and strength.

We deeply appreciate your continued support and collaboration.
Thank you, as always, for being part of this journey.

Satoshi Iso
Director, iTHEMS
April 2025

On Friday, April 4, 2025, the annual iTHEMS Starter Meeting was held at 12:30 PM in Suzuki Umetaro Hall. Unlike the regular Coffee Meetings that take place every Friday at the same time, the Starter Meeting marks the beginning of the academic year and serves as a special occasion to introduce new members, allow existing members to reintroduce themselves, and share the outlook for the year ahead. This year’s meeting was held on a larger scale than usual to commemorate a major organizational milestone—the transformation of iTHEMS from a program into the newly established RIKEN Center for Interdisciplinary Theoretical and Mathematical Sciences.

The meeting opened with a commemorative talk by Tetsuo Hatsuda, former Program Director, who reflected on the history of interdisciplinary mathematical science research at RIKEN, beginning with the iTHES program and leading up to the evolution of iTHEMS. He also expressed heartfelt appreciation for the contributions of former Deputy Program Directors Takashi Tsuboi and Takemasa Miyoshi. Following his talk, the new Center Director, Satoshi Iso, provided an overview of the structure and vision for the newly reorganized iTHEMS, including the establishment of new research units and teams designed to further expand and deepen the center’s interdisciplinary mission. Flower bouquets were then presented to Hatsuda-san and Tsuboi-san as a gesture of gratitude, while Miyoshi-san, who was absent, was also acknowledged for his contributions.

After a brief intermission, Tsukasa Tada, Deputy Director, introduced the newly adopted iTHEMS Code of Conduct. He emphasized its core principles—mutual respect, scientific integrity, inclusivity, and responsibility—and explained how the Code reflects the ethical foundation that each member is encouraged to uphold and shape as the community evolves. This was followed by a series of one-minute self-introductions by all members, each using a single slide, continuing the tradition of fostering familiarity and collaboration across disciplines.

The meeting concluded slightly before 5:00 PM, after which participants returned to the Main Research Building to attend a reception in the open space on the third floor. The reception provided an opportunity for further discussion and networking among iTHEMS members and affiliated researchers, marking a warm and promising start to the new academic year under the expanded vision of the iTHEMS Center.

The former Deputy Program Director of iTHEMS, Takashi Tsuboi, has been appointed "Honorary Research Fellow" at RIKEN by President Makoto Gonokami, effective April 1, 2025.This honor recognizes Takashi’s many years of distinguished service as Deputy Program Director of iTHEMS (FY2017–FY2024), as well as his outstanding achievements and dedicated contributions. He will continue to support iTHEMS as a Senior Visiting Scientist.

Congratulations, Takashi!

An interview article with Yohsuke Murase (Senior Research Scientist) has been featured in Research Highlights, part of the "Close-up RIKEN 2025" series on RIKEN’s research introduction page. It has also been published in SPRING 2025 issue of RIKEN’s public relations magazine, RIKEN NEWS.

We humans, often described as social animals, engage in "cooperative behavior"—working together and helping one another. Focusing on the key role played by "reputation," Dr. Yohsuke Murase and an international research team analyzed the dynamics of this information using the supercomputer Fugaku. Their findings revealed the evolutionary path of humanity, shaped by cooperative behavior.

For more details, please refer to the related links.

Our colleague Yan Lyu received the FY2024 RIKEN Excellent Achievement Award (RIKEN BAIHO Award) on March 28, 2025, in recognition of his outstanding work on “Elucidation of Genuine Tetraquarks Based on Lattice Quantum Chromodynamics.” The photo was taken on April 4, 2025, on the way to Suzuki Umetaro Hall at the Wako campus.
Congratulations, Yan!

Our colleague Kyosuke Adachi received the FY2024 RIKEN Research and Technology Incentive Award (RIKEN OHBU Award) on March 28, 2025, in recognition of his outstanding work on “Unveiling the Rules of Amino Acid Sequences Governing Protein Condensation.” The photo was taken on April 4, 2025, on the way to Suzuki Umetaro Hall at the Wako campus.
Congratulations, Kyosuke!

Title: Irrationality of the reciprocal sum of doubly exponential sequences
Author: Junnosuke Koizumi
arXiv: http://arxiv.org/abs/2504.05933v1

Title: Re-evaluation of the deuteron-deuteron thermonuclear reaction rates in metallic deuterium plasma
Author: Faisal Etminan
arXiv: http://arxiv.org/abs/2504.05003v1

Title: Thermonuclear superburst of MAXI J1752$-$457 observed with NinjaSat and MAXI
Author: Amira Aoyama, Teruaki Enoto, Takuya Takahashi, Sota Watanabe, Tomoshi Takeda, Wataru Iwakiri, Kaede Yamasaki, Satoko Iwata, Naoyuki Ota, Arata Jujo, Toru Tamagawa, Tatehiro Mihara, Chin-Ping Hu, Akira Dohi, Nobuya Nishimura, Motoko Serino, Motoki Nakajima, Takao Kitaguchi, Yo Kato, Nobuyuki Kawai
arXiv: http://arxiv.org/abs/2504.04352v1

Title: Finite-Temperature Perturbation Theory of Rotating Scalar Fields
Author: Ryo Kuboniwa, Kazuya Mameda
arXiv: http://arxiv.org/abs/2504.04712v1

Title: A satellite formula for real Seiberg-Witten Floer homotopy types
Author: Jin Miyazawa, JungHwan Park, Masaki Taniguchi
arXiv: http://arxiv.org/abs/2504.03270v1