RIKEN Interdisciplinary Theoretical and
Mathematical Sciences Program

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Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) is an international research program at RIKEN. It facilitates close collaborations among researchers from different disciplines in theoretical, mathematical and computational sciences. The ultimate goal of iTHEMS is to unravel the mystery of the Universe, matter, and life, as well as to solve key problems in modern society through interdisciplinary approaches.

About iTHEMS

Upcoming Events



Quantum Matter Seminar

Nonlinear response in strongly correlated systems

October 20 at 17:00 - 18:15, 2021

Dr. Robert Peters (Lecturer, Department of Physics, Graduate School of Science, Kyoto University)

Nonlinear responses in condensed matter are intensively studied because they provide rich information about materials and hold the possibility of being applied in diodes or high-frequency optical devices [1-4]. While nonlinear responses in noninteracting models have been explored widely, the effect of strong correlations on the nonlinear response is still poorly understood. This talk will introduce a Green's function method to calculate nonlinear conductivities in strongly correlated materials [5-6]. Correlation effects are thereby included by the self-energy of the material. I will then use this method to study the nonlinear conductivities in noncentrosymmetric f-electron systems. The first system is a heavy Fermion system, where a nonreciprocal conductivity appears in the ferromagnetic phase. The nonreciprocal conductivity thereby always occurs perpendicular to the magnetization of the system and has a strong spin dependence, which might be advantageous for spintronic applications. The second system is a model corresponding to the Weyl-Kondo semimetal Ce3Bi4Pd3, in which a giant spontaneous Hall effect without time-reversal symmetry breaking has been observed [7]. This Hall effect can be explained as a nonlinear Hall effect in an inversion-symmetry broken Weyl-semimetal. It has been shown that the nonlinear Hall effect is related to the Berry curvature dipole [4]. Our study shows that the magnitude of the experimentally observed nonlinear Hall effect can be explained by the strong correlations inherent in this f-electron material [8]. *Detailed information about the seminar refer to the email.

Venue: via Zoom

Event Official Language: English


Supported by iTHEMS

Can social issues be solved by mathematical science? -attempts and challenges

October 26 at 10:00 - 17:00, 2021

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)
Dr. Masato Wakayama (Vice President, Tokyo University of Science)
Prof. Takashi Sakajo (Professor, Department of Mathematics, Kyoto University)
Prof. Shingo Iwami (Professor, Division of Biological Science, Graduate School of Science, Nagoya University)
Dr. Hirotaka Irie (Assistant Manager, DENSO Corporation)

In recent years, the importance of mathematical sciences has been increasingly recognized in various fields, as exemplified by the rapid progress of AI technology and the development of DX (Digital Transformation) in companies. In academia, research centers have been established in fields such as space, materials, life, and medicine, where experts in the mathematical sciences play an important role in research activities in their respective fields. At the same time, the universality of mathematics and the quantitative and predictive nature of data analysis are also being considered useful in industry, and some companies are actively using mathematical science in their own business. Some companies are actively utilizing mathematical science in their business. In this symposium, researchers who are conducting research with the mission of returning research using mathematical science to society and implementing it will gather to discuss, based on the results of their cutting-edge research, "Can social issues be solved with mathematical science? -Attempts and Challenges" and discuss the role of mathematical science in society.

Venue: Hybrid Format (Noyori Conference Hall, Nagoya University and Zoom)

Event Official Language: English


iTHEMS Colloquium

High-Energy Neutrino Astrophysics in the Multimessenger Era

October 28 at 15:00 - 16:30, 2021

Prof. Kohta Murase (Associate Professor, Pennsylvania State University, USA)

The discovery of high-energy cosmic neutrinos opened a new window of astroparticle physics. Their origin is a new mystery in the field, which is tightly connected to the long-standing puzzle about the origin of cosmic rays. I will give an overview of the latest results on high-energy neutrino and cosmic-ray observations, and demonstrate the power of "multimessenger" approaches. In particular, I will show that the observed fluxes of neutrinos, gamma rays, and extragalactic cosmic rays can be understood in a unified manner. I will also highlight the recent developments about astrophysical neutrino emission from supermassive black holes and violent transient phenomena. Possibilities of utilizing high-energy neutrinos as a probe of heavy dark matter may be discussed.

Venue: via Zoom

Event Official Language: English

More events Event Calendar


Seeking a few Postdoctoral Researchers (W21169)

Deadline: Open until filled

Postdoctoral Researcher, a few positions. In particular, we welcome applications from young researchers who are interested in exploring theories of quantum gravity in a broad sense. Currently, Senior Research Scientist Yuki Yokokura is affiliated with iTHEMS, and we expect young researchers with complementary and unique expertise, who are willing to pursue their own ambitious motivation and create synergy among the members.

Seeking a few Postdoctoral Researchers (RIKEN-Berkeley Fellow associated with N3AS) (W21157)

Deadline: Open until filled

Postdoctoral Researcher (RIKEN-Berkeley Fellow associated with N3AS), a few positions. Theoretical works associated with neutrino physics, nucleosynthesis, dense matter and neutron stars, dark matter, astrophysical simulations and related fields.

Seeking a few Postdoctoral Researchers (W21158)

Deadline: Open until filled

Postdoctoral Researcher, a few positions. In particular, the successful applicant(s) are expected to spend at least 50% of their time working with Dr. Ryosuke Iritani carrying out interdisciplinary research addressing fundamental questions in population genetics, phylogenetics, and bioinformatics, by using mathematical and theoretical approach in dynamical systems, stochastic process, statistical physics, and/or information theory. Applicants are expected to have a considerable expertise in those theories.

Seeking a Female Research Scientist or a Female Senior Research Scientist (W21071)

Deadline: Open until filled

Female Research Scientist or Female Senior Research Scientist, a few positions. Seeking a female researcher or a female senior researcher to conduct theoretical research in the fields of natural sciences, mathematical sciences, or humanities and social sciences.

Seeking a Postdoctoral Researcher or Research Scientist (W21003)

Deadline: Open until filled

Postdoctoral Researcher or Research Scientist, a few positions. In particular, the applicant(s) are expected to spend at least 50% of their time carrying out original research developing numerical models to describe biological systems, such as the spread of virus in a cell culture, in collaboration with Dr. Catherine Beauchemin.

More opportunities

Latest News


Seminar Report

ABBL/iTHEMS Astro Seminar by Dr. Nobuya Nishimura on October 15, 2021

At the seminar, there were lots of questions and answers for r-process nucleosynthesis and kilonova events. The speaker presented lots of his excellent works on them, and the audience enjoyed his presentation with curiosity. Reported by Shigehiro Nagataki


Paper of the Week

Week 3, October 2021

Title: The genome of Shorea leprosula (Dipterocarpaceae) highlights the ecological relevance of drought in aseasonal tropical rainforests Author: Kevin Kit Siong Ng, Masaki J. Kobayashi, Jeffrey A. Fawcett, Masaomi Hatakeyama, Timothy Paape, Chin Hong Ng, Choon Cheng Ang, Lee Hong Tnah, Chai Ting Lee, Tomoaki Nishiyama, Jun Sese, Michael J. O’Brien, Dario Copetti, Mohd Noor Mat Isa, Robert Cyril Ong, Mahardika Putra, Iskandar Z. Siregar, Sapto Indrioko, Yoshiko Kosugi, Ayako Izuno, Yuji Isagi, Soon Leong Lee, Kentaro K. Shimizu Journal Reference: Commun Biol 4, 1166 (2021) doi: https://doi.org/10.1038/s42003-021-02682-1 Title: Effect of advancing age on the reproductive performance of Japanese Thoroughbred broodmares Author: Jeffrey A. FAWCETT, Hideki INNAN, Takeru TSUCHIYA, Fumio SATO Journal Reference: J. Equine Sci. Vol. 32, No. 2, pp. 31–37 (2021) doi: https://doi.org/10.1294/jes.32.31 Title: Universal relation for supernova gravitational waves Author: Hajime Sotani, Tomoya Takiwaki, Hajime Togashi arXiv: http://arxiv.org/abs/2110.03131v2 Title: Topology and symmetry of circular photogalvanic effect in the chiral multifold semimetals: a review Author: Congcong Le, Yan Sun doi: https://doi.org/10.1088/1361-648X/ac2928 arXiv: http://arxiv.org/abs/2110.03434v1



Nagisa Hiroshima received the Award for Female Researchers of the University of Toyama

University of Toyama has announced that Nagisa Hiroshima (Visiting Scientist, iTHEMS) received "The Award for Female Researchers of the University of Toyama". Congratulations!

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