# Award

## Takemasa Miyoshi received "Commendation by the Prime Minister for Disaster Prevention (2020)"

2020-09-14

It is our great pleasure to inform you that our colleague, Takemasa Miyoshi, received "Commendation by the Prime Minister for Disaster Prevention (2020)”. The awards ceremony was held on Sep.4, 2020 at the Prime Minister's Office in Tokyo.

# Seminar Report

## Math Seminar by Dr. Ken Furukawa on September 8, 2020

2020-09-11

On September 8, there was a math seminar by Dr. Ken Furukawa. He gave a talk entitled Maximal Regularity and Partial Differential Equations.

In the first part of his talk, the speaker explained the maximal regularity of parabolic partial differential equations and various sufficient conditions for the maximal regularity. Especially he introduced some functional calculus to obtain the analytic semigroup.

In the second part, the speaker explained his recent collaboration work on the primitive equation and its relationship to the Navier-Stokes equation. He first shows that we can formally obtain primitive equations from the Navier-Stokes equation on the thin domain. He then explained his recent collaboration work which justifies this formal derivation of the primitive equation and how the sufficient conditions in the first talk work.

Maximal Regularity and Partial Differential Equations

September 8 at 16:00 - 18:10, 2020

# Upcoming Events

## Workshop

### The 2nd Heidelberg-Kyoto-RIKEN Workshop, Medicine and Math

September 18 - 19, 2020

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)

Prof. Takashi Sakajo (Senior Visiting Scientist, iTHEMS / Professor, Department of Mathematics, Kyoto University / Senior Visiting Scientist, Prediction Science Laboratory, RIKEN Cluster for Pioneering Research (CPR))

Prof. Motomu Tanaka (Professor, Physical Chemistry of Biosystems, Heidelberg University, Germany / Professor, Center for Integrative Medicine and Physics, Kyoto University Institute for Advanced Study (KUIAS))

Venue: via Online

Event Official Language: Japanese

## Seminar

### Potential Toolkit to Attack Nonperturbative Aspects of QFT －Resurgence and related topics－

September 7 - 25, 2020

Dr. Aleksey Cherman (University of Minnesota, USA)

Prof. Gerald Dunne (University of Connecticut, USA)

Prof. Mithat Unsal (North Carolina State University, USA)

Dr. Toshiaki Fujimori (Keio University)

Dr. Yasuyuki Hatsuda (Rikkyo University)

Dr. Masazumi Honda (Kyoto University)

Dr. Okuto Morikawa (Kyushu University)

Dr. Naohisa Sueishi (Nagoya University)

Dr. Masahito Yamazaki (Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), The University of Tokyo / The University of Tokyo)

Recently, there have been significant developments in theoretical techniques/frameworks to tackle non-perturbative aspects of quantum field theory (QFT) such as the resurgence theory, the Lefschetz thimble method, ’t Hooft anomaly matching, and novel lattice setups. Such developments are still growing very rapidly and making fruitful connections not only among physicists involved in fields with broad energy scales but also with mathematicians. These developments would enable us to unveil rich and exciting physics of QFT in the non-perturbative regime. It is of primary importance to hold a workshop for researchers in various fields related to the topics to get together and overview/share the recent progresses, to discuss future directions, and to seek for possible new collaborations bridging various fields of physics/mathematics.

Venue: YITP (Kyoto University), Zoom, and Mozilla hubs

Event Official Language: English

## External Event

### Perspective of nuclear physics in the 21 century

September 27 at 13:30 - 17:00, 2020

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)

Prof. Hiroyoshi Sakurai (Director, RIKEN Nishina Center for Accelerator-Based Science (RNC))

Prof. Naohito Saito (Director, J-PARC Center)

Prof. Takaaki Kajita (Director, Institute for Cosmic Ray Research (ICRR), The University of Tokyo)

世界最先端の日本の原子核物理研究を行う4施設の牽引者がそれぞれリレー方式で講義を行います。21世紀の原子核物理学の潮流といえる、重力波や中性子星連星合体など宇宙の謎に迫る高密度世界の解明に関する研究内容から、先端加速器やスーパーコンピューターを用いた最先端の研究スタイルまで、日本が誇る原子核物理学の今と今後の展望をお話します。

Venue: via YouTube Live

Event Official Language: Japanese

## Workshop

### The Second Tohoku University - RIKEN Joint Workshop: "Math Meets Quantum Materials"

September 29 - 30, 2020

Prof. Hidetoshi Nishimori (Senior Visiting Scientist, iTHEMS / Specially Appointed Professor, Tokyo Institute of Technology)

Dr. Tomoki Ozawa (Visiting Scientist, iTHEMS / Associate Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

Dr. Ching-Kai Chiu (Senior Research Scientist, iTHEMS)

Dr. Ryusuke Hamazaki (Senior Research Scientist, iTHEMS / RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR))

Dr. Kyosuke Adachi (Special Postdoctoral Researcher, iTHEMS / Special Postdoctoral Researcher, Nonequilibrium Physics of Living Matter RIKEN Hakubi Research Team, RIKEN Center for Biosystems Dynamics Research (BDR))

Prof. Christopher Bourne (Visiting Scientist, iTHEMS / Assistant Professor, Advanced Institute for Materials Research (AIMR), Tohoku University)

The second Tohoku University - RIKEN joint workshop, entitled "Math Meets Quantum Materials," takes place from September 29 - 30.

Tohoku University and RIKEN have been holding a series of joint workshops based on the agreement on collaboration and cooperation signed in 2019.

The second workshop focuses on collaboration in the fields of mathematical sciences and quantum materials; two fields that have significantly merged in recent years.

Like topological materials, which are discovered using the mathematical concept of topology, materials science is currently evolving from the conventional way of finding materials. Instead of developing materials with good properties through numerous experiments, materials science is increasingly finding materials using mathematical predictions.

This workshop will discuss these latests developments and related topics.

Although some lectures will take place in Japanese, the majority of talks will be in English.

The deadline for registration is Monday, September 28.

For more information, please click on the relevant link.

Venue: via Online

Event Official Language: English

## Seminar

### The Uchuu Simulations: Data Release 1 and Dark Matter Halo Concentrations

October 1 at 14:00 - 15:00, 2020

Dr. Tomoaki Ishiyama (Associate Professor, Institute of Management and Information Technologies)

We introduce the Uchuu suite of large high-resolution cosmological N-body simulations. The largest simulation, named Uchuu, consists of 2.1 trillion dark matter particles in a box of 2.0 Gpc/h. The highest resolution simulation, called Shin-Uchuu, consists of 262 billion particles in a box of 140 Mpc/h. Combining these simulations we can follow the evolution of dark matter haloes (and subhaloes) spanning from dwarf galaxies to massive galaxy cluster hosts. We present basic statistics, dark matter power spectra and halo (subhalo) mass function, to demonstrate the huge dynamic range and superb statistics of the Uchuu simulations. From the analysis of the evolution of the power spectra we conclude that our simulations are accurate enough from the Baryon Acoustic Oscillations up to very small scales. We also provide parameters of a mass-concentration model, which describes the evolution of halo concentrations, that reproduces our simulation data within 5% error for haloes with masses spanning nearly eight orders of magnitude at redshift 0<z<14. We make publicly available various N -body products, as part of Uchuu Data Release 1, on the Skies & Universes site. We also plan to release gravitational lensing maps, mock galaxy, X-ray cluster and active galactic nuclei catalogues in the near future.

Venue: via Zoom

Event Official Language: English

## Seminar

### TQFT, integrable lattice model, and quiver gauge theories

October 2 at 16:00 - 18:00, 2020

Dr. Toshihiro Ota (Student Trainee, iTHEMS / Graduate School of Science, Osaka University School of Science)

- 1st part (math): In physics literature, “lattice models” appear quite often as mathematical models of physical systems, e.g. Ising model, vertex models, lattice gauge theory. The aim of the 1st part is to introduce ‘what is (T)QFT,’ ‘what is lattice model,’ and ‘what does integrability mean’ in the language of mathematics. In turn, they will play a crucial role in the 2nd part of my talk. I also hope that this will lead to a good exchange among us, especially between physicists and mathematicians.

- 2nd part (physics): In the 2nd part, I would like to explain where an integrable lattice model may come from, especially for people in the physics background. I will show a certain class of integrable lattice models is realized by Wilson-’t Hooft lines in 4d quiver gauge theories. I will also explain a bit how these gauge theories are constructed from brane configurations in string theory. String dualities allow us to relate the original 4d setups to 4d partially topological Chern-Simons theory, which is a partial TQFT and generates integrable lattice models.

Venue: via Zoom

Event Official Language: English

## Lecture

### Forefront of Modern Science: Frontiers in Mathematics, Astronomy, Physics, Biology and Computation

October 2 at 16:20 - 17:50, 2020

Dr. Tetsuo Hatsuda (Program Director, iTHEMS)

Dr. Yuka Kotorii (Visiting Scientist, iTHEMS / Associate Professor, Mathematics Program, Graduate School of Advanced Science and Engineering, Hiroshima University / Visiting Scientist, Mathematical Analysis Team, RIKEN Center for Advanced Intelligence Project (AIP))

Dr. Shigehiro Nagataki (Deputy Program Director, iTHEMS / Chief Scientist, Astrophysical Big Bang Laboratory, RIKEN Cluster for Pioneering Research (CPR))

Dr. Makiko Nio (Senior Researcher, RIKEN Nishina Center for Accelerator-Based Science (RNC))

Dr. Ryosuke Iritani (Research Scientist, iTHEMS)

Dr. Ai Niitsu

Dr. Shigenori Otsuka (Research Scientist, iTHEMS / Research Scientist, Data Assimilation Research Team, RIKEN Center for Computational Science (R-CCS))

Dr. Emi Yukawa (Assistant Professor, Department of Physics, Faculty of Science Division I, Tokyo University of Science)

Venue: Changed to Zoom

Event Official Language: Japanese

## External Event

### The Mathematical Society of Japan: Cross-discipline and cross-industry research exchange meeting 2020

October 31 at 10:00 - 17:00, 2020

「数学・数理科学専攻若手研究者のための異分野・異業種研究交流会（研究交流会）」は、 数学・数理科学専攻の博士課程学生をはじめとする若手研究者と産業界を含む異分野の方々 との「双方向の交流の場」として2014年から開催しております。若手研究者の皆様に、諸科学や産業への応用展開のような数学の思わぬ力を発見してもらう ことや、産業界を含む様々な分野で活躍できる場の存在を認識してもらうことが主たる目的 です。高等学校、大学を含む教育・研究機関の教職員や企業関係者の皆様にも、産業界における数学 ・数理科学やその知識を有する人材のニーズを把握してもらうことも目的の一つです。

Venue: via Online

Event Official Language: Japanese

# Paper of the Week

## Week 3 of September

2020-09-17

Title: Effective field theory of magnon: Dynamics in chiral magnets and Schwinger mechanism

Author: Masaru Hongo, Toshiaki Fujimori, Tatsuhiro Misumi, Muneto Nitta, Norisuke Sakai

arXiv: http://arxiv.org/abs/2009.06694v1

Title: Are atoms spherical?

Author: Tomoya Naito, Shimpei Endo, Kouichi Hagino, Yusuke Tanimura

arXiv: http://arxiv.org/abs/2009.05955v1

Title: Accuracy of relativistic Cowling approximation in protoneutron star asteroseismology

Author: Hajime Sotani, Tomoya Takiwaki

arXiv: http://arxiv.org/abs/2009.05206v1

Title: Effective models of a semi-quark gluon plasma

Author: Yoshimasa Hidaka, Robert D. Pisarski

arXiv: http://arxiv.org/abs/2009.03903v1

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