iTHEMS Weekly News Letter

Seminar Report

iTHEMS Math Seminar by Dr. Yalong Cao on August 6, 2021


The final Math Seminar of this semester was held on August 9th. This time, we invited our new colleague Dr. Yalong Cao as a speaker.
First, he gave an overview of the celebrated Yang-MIlls theory in real dimensions 3 and 4.
Next, it was explained that one can complexify the above Yang-Mills theory on Calabi-Yau 3 and 4-folds.
The point is that in algebro-geometric setting, moduli spaces of Yang-Mills connections admit nice compactifications.
Finally, he explained the connection between the above story and the enumerative geometry, specifically on counting (stable) coherent sheaves and complex ASD connections on Calabi-Yau 4-folds. He and his collaborators proposed a conjectural sheaf-theoretic interpretation of Klemm-Pandharipande’s BPS invariants of CY 4-folds defined using Gromov-Witten theory.

Reported by Hiroyasu Miyazaki

Hot Topic

Dr. Hirotaka Irie thumbnail

Nihon Keizai Shimbun: Utilizing the Power of Quantum Computers in Combination


Dr. Hirotaka Irie (iTHEMS Visiting Scientist (Industry)) was interviewed in the Nihon Keizai Shimbun.
He talks about the "hybrid type" that combines the best parts of conventional computers and quantum computers.
Please see the related link for details.

Upcoming Events


NEW WG Seminar

Towards a description of amorphous solids and viscoelastic materials using effective field theory and holographic methods

September 10 at 13:30 - 15:00, 2021

Prof. Matteo Baggioli (Associate Professor, School of Physics and Astronomy, Shanghai Jiao Tong University, China)

Among the most ubiquitous phases of matter, gases and crystalline solids are definitely the simplest to be described. Their physics is indeed almost entirely textbooks material and it can be summarized within the elegant frameworks of kinetic theory and Debye theory. Liquids and specially viscoelastic systems and amorphous materials (e.g. glasses) exhibit a much richer and complex dynamics with provides a large set of fundamental and unresolved physical questions. Given the tremendous microscopic complexity of these systems, which is manifest in a large landscape of scales and anomalous behaviours, the effective field theory (EFT) paradigm of isolating only a few, but fundamental, information could provide a winning approach. This talk is based on the simple, but indeed extremely difficult, question of whether these phases of matter can be distinguished, classified and understood using emergent and/or fundamental symmetry principles as in their ordered crystal counterpart. More precisely, we will combine EFTs, hydrodynamics and holographic methods to tackle the above question. I will present the most recent developments in this direction and I will discuss with you the most important open questions and avenues to explore in the near future.

Venue: via Zoom

Event Official Language: English


iTHEMS Colloquium

Finding Gravitational Waves from the Early Universe

September 27 at 16:00 - 17:30, 2021

Prof. Eiichiro Komatsu (Director, Max Planck Institute for Astrophysics, Germany)

The Cosmic Microwave Background (CMB) gives a photographic image of the Universe when it was still an “infant”. We have been using it to test our ideas about the origin of the Universe. The CMB research told us a remarkable story: the structure we see in our Universe such as galaxies, stars, planets, and eventually ourselves originated from tiny quantum fluctuations in the period of the early Universe called cosmic inflation. While we have accumulated strong evidence for this picture, the extraordinary claim requires extraordinary evidence. The last prediction of inflation that is yet to be confirmed is the existence of primordial gravitational waves whose wavelength can be as big as billions of light years. To this end we have proposed to JAXA a new satellite mission called LiteBIRD, whose primary scientific goal is to find signatures of gravitational waves in the polarisation of the CMB. In this presentation we describe physics of gravitational waves from inflation, and the LiteBIRD proposal.

Venue: via Zoom

Event Official Language: English

Paper of the Week

Week 5, August 2021


Title: Intraspecific Adaptation Load: A Mechanism for Species Coexistence
Author: Masato Yamamichi, Daisuke Kyogoku, Ryosuke Iritani, Kazuya Kobayashi, Yuma Takahashi, Kaori Tsurui-Sato, Akira Yamawo, Shigeto Dobata, Kazuki Tsuji, Michio Kondoh
Journal Reference: Trends in Ecology & Evolution 35(10), 897-907 (2020)

Title: Reproductive interference hampers species coexistence despite conspecific sperm precedence
Author: Ryosuke Iritani, Suzuki Noriyuki
Journal Reference: Ecology and Evolution 11(5),1957-1969 (2021)

Title: Temporal changes in spatial variation: partitioning the extinction and colonisation components of beta diversity
Author: Shinichi Tatsumi, Ryosuke Iritani, Marc W. Cadotte
Journal Reference: Ecology Letters 24(5), 1063-1072 (2021)

Title: A solution to a sex ratio puzzle in Melittobia wasps
Author: Jun Abe, Ryosuke Iritani, Koji Tsuchida, Yoshitaka Kamimura, Stuart A. West
Journal Reference: PNAS 118 (20) e2024656118 (2021)

Title: Cooperative interactions among females can lead to even more extraordinary sex ratios
Author: Ryosuke Iritani, Stuart A. West, Jun Abe
Journal Reference: Evolution Letters 5(4),370-384 (2021)

Title: Construction of energy density functional for arbitrary spin polarization using functional renormalization group
Author: Takeru Yokota, Tomoya Naito

Title: Femtoscopic study of coupled-channel $NΞ$ and $ΛΛ$ interactions
Author: Y. Kamiya, K. Sasaki, T. Fukui, T. Hyodo, K. Morita, K. Ogata, A. Ohnishi, T. Hatsuda

Title: Product of Random States and Spatial (Half-)Wormholes
Author: Kanato Goto, Yuya Kusuki, Kotaro Tamaoka, Tomonori Ugajin

Title: Band width and the Rosenberg index
Author: Yosuke Kubota

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