# RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program

## Videos

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.

## Upcoming Events

Seminar

Tomorrow

### Recent progress on dualities in W-superalgebras

January 28 at 16:00 - 18:00, 2022

Dr. Shigenori Nakatsuka (JSPS Fellow, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo)

Vertex superalgebras are algebras which describe the chiral part of two dimensional superconformal field theory. A rich and fundamental class is provided by the affine vertex superalgebras associated with simple Lie superalgebras and the W-superalgebras obtained from them by cohomology parametrized by nilpotent orbits. Historically, the W-algebras associated with simple Lie algebras and principal nilpotent orbit have been studied intensively and are well-known to play an essential role in the quantum geometric Langlands program. In particular, they enjoy a duality, called the Feigin-Frenkel duality, which is a chiral analogue of the isomorphism between centers of the enveloping algebras of simple Lie algebras in Langlands duality. Recently, physicists found a suitable generalization for other types of nilpotent orbits from study on four dimensional supersymmetric gauge theory. In this talk, I will report the recent progress on our understanding of dualities in W-superalgebras since then in terms of several aspects: algebras, modules, and fusion rules.

Venue: via Zoom

Event Official Language: English

External Event

### RIKEN AIP-Suri-joshi Joint Seminar

January 29 at 15:00 - 16:40, 2022

Dr. Ryosuke Iritani (Research Scientist, iTHEMS)
Dr. Ade Irma Suriajaya (Assistant Professor, Faculty of Mathematics, Kyushu University)
Dr. Motoko Kato (Assistant Professor, Faculty of Science, Ehime University)

"What are the personalities of AI and mathematical researchers? What kind of work do researchers do?" The RIKEN Center for Integrative Research on Innovative Intelligence (RIKEN AIP) and "Suri-joshi" are planning a joint event that will give high-school girls who are interested in mathematical scientists an opportunity to learn more about the fascinating work of AI and mathematical researchers.

Venue: via Zoom

Event Official Language: Japanese

Workshop

### Towards the Use of Data Assimilation for COVID-19 Investigations

February 14 at 13:00 - 17:30, 2022

Prof. Catherine Beauchemin (Deputy Program Director, iTHEMS)
Dr. Takemasa Miyoshi (Team Leader, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS))

This workshop aims to present recent investigations related to mathematical modeling of COVID-19 spread and impacts, and to foster the use of data assimilation techniques in future studies. It also aims to facilitate interactions and discussions among researchers from different fields such as epidemiology, economics, and mathematics. This workshop is jointly hosted by RIKEN Data Assimilation Research Team and by Nagoya University Graduate School of Mathematics, and supported by FY2021 RIKEN President's Discretionary Funds for COVID-19. A hybrid meeting is planned, but depending on the situation, an online version will be organized. Young researchers and students are encouraged to attend. Program: 13:00 - 13:10 Opening 13:10 - 14:00 Hiroshi Nishiura (Kyoto University) (35 min + 15 min Q&A) TBD 14:00 - 14:50 Catherine Beauchemin (RIKEN iTHEMS) (35 min + 15 min Q&A) The straight line: simple and effective 14:50 - 15:10 Break 15:10 - 16:00 Taisuke Nakata (The University of Tokyo) (35 min + 15 min Q&A) Balancing NPIs and Economic Activities 16:00 - 16:50 Qiwen Sun (RIKEN Data Assimilation Research Team, Nagoya University) (35 min + 15 min Q&A) Analysis of COVID-19 in Japan with Extended SEIR model and ensemble Kalman filter 16:50 - 17:30 Discussion

Venue: Hybrid Format (RIKEN R-CCS room 107 and Zoom)

Event Official Language: English

External Event

### RIKEN Day: Let's Talk with Researchers! "Listening to the Ringing of a Black Hole"

February 25 at 18:00 - 18:30, 2022

Dr. Naritaka Oshita (Special Postdoctoral Researcher, iTHEMS)

In the February RIKEN Day, we will have a talk with Naritaka Oshita, a researcher who is researching on the theme of "Listening to the Ringing of a Black Hole." See related links for details.

Venue: via Zoom

Event Official Language: Japanese

## Opportunities

### Seeking a few Postdoctoral Researchers (W21169)

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)

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)

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)

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.

More opportunities

## Latest News

2022-01-27

Paper of the Week

### Week 5, January 2022

Title: Gopakumar-Vafa type invariants of holomorphic symplectic 4-folds Author: Yalong Cao, Georg Oberdieck, Yukinobu Toda arXiv: http://arxiv.org/abs/2201.10878v1 Title: Universal Properties of Weakly Bound Two-Neutron Halo Nuclei Author: Masaru Hongo, Dam Thanh Son arXiv: http://arxiv.org/abs/2201.09912v1 Title: On the evolution of the Hubble constant with the SNe Ia Pantheon Sample and Baryon Acoustic Oscillations: a feasibility study for GRB-cosmology in 2030 Author: Maria Giovanna Dainotti, Biagio De Simone, Tiziano Schiavone, Giovanni Montani, Enrico Rinaldi, Gaetano Lambiase, Malgorzata Bogdan, Sahil Ugale arXiv: http://arxiv.org/abs/2201.09848v2 Title: Foundations and Applications of Quantum Kinetic Theory Author: Yoshimasa Hidaka, Shi Pu, Qun Wang, Di-Lun Yang arXiv: http://arxiv.org/abs/2201.07644v1 Title: Global study of the scalar quasi-normal modes of Kerr-AdS${}_5$ black holes: Stability, thermality, and horizon area quantization Author: Issei Koga, Naritaka Oshita, Kazushige Ueda arXiv: http://arxiv.org/abs/2201.07267v1

2022-01-25

Seminar Report

### NEW WG Seminar by Mr. Tomohiro Tanogami on January 20, 2022

Tomohiro Tanogami from Kyoto University gave a talk titled "A simple XY model for cascade transfer." Cascade transfer is a ubiquitous phenomenon that appears in various physical systems. During a cascade transfer an inviscid conserved quantity such as energy is transferred conservatively from large/small to small/large scales, which results in a universal scaling law in the spectrum (e.g., Kolmogorov energy spectrum). In the talk, Tomohiro proposed a simple XY model which shows inverse energy cascade with a non-Kolmogorov energy spectrum and pointed out that the model may characterize a novel "universality class" of cascade transfer. Tomohiro also explained possible relations between his model and, e.g., spin and atmospheric turbulences. About 20 physicists have joined the seminar and enjoyed discussions from various viewpoints. Reported by Hidetoshi Taya

2022-01-24

Press Release

### Origin of Diverse Response Patterns in Signal Transduction - Determining Response Properties by Integrating Experiment and Theory

The ERBB family of receptors, consisting of ERBB1, ERBB2, ERBB3, and ERBB4, is a group of receptors that receive external signaling molecules. When the ERBB receptors receive signaling molecules, they bind to one another and induce phosphorylation reactions, leading to macroscopic responses such as cell proliferation and differentiation. However, it is difficult to measure the details of the binding and phosphorylation reactions of the ERBBs, and it has not been known how the various responses to signals are produced. In this study, we conducted experimental measurements using cells with various compositions of ERBBs and multiple signaling molecules and constructed a mathematical model, which incorporates all possible reactions of ERBBs. By applying the mathematical model, we succeed in explaining and predicting the experimental results on phosphorylation responses. Furthermore, we identified the reactions that play an essential role in the diversity of the phosphorylation responses. Our findings may allow us to control cell responses such as proliferation and differentiation in the future. For more details, please see the press release article from Kyoto University at RELATED LINKS.