The Physical Society of Japan has announced that the paper entitled "Negative string tension of a higher-charge Schwinger model via digital quantum simulation" by Dr. Etsuko Itou (Postdoctoral Researcher, iTHEMS) and her collaborators has been selected as the Editors' Choice in Progress of Theoretical and Experimental Physics.

A joint research team led by Dr. Takemasa Miyoshi, Team Leader of the Data Assimilation Research Team at the RIKEN Center for Computational Science (R-CCS) (Chief Scientist, Predictive Science Laboratory, Deputy Program Director, RIKEN Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS)), and Dr. Yasumitsu Maejima, Postdoctoral Researcher, has announced that simulation showed significant improvement of forecasting disastrous heavy rainfall in July 2020. The results of this study showed that the state-of-the-art phased-array weather radar can significantly improve the accuracy of forecasting heavy rainfall associated with linear precipitation zones.

The results of this research are expected to improve the forecasting accuracy of linear precipitation zones, which are increasingly threatened by global warming, and to lead to the proposal of new forecasting techniques and observation systems to mitigate the damage.

To read more, please see the related link.

It is known that particles with the same positive (negative) charge usually are repulsed, while particles with opposite positive and negative charges are attracted to each other. Recently, however, it was pointed out that such "common knowledge" that an attractive force acts between particles with opposite positive and negative charges does not always hold true under special situations.

The research group succeeded in realizing a situation in which a repulsive force acts between particles with opposite charges in a one-dimensional quantum system called the Schwinger model by numerical simulation. This is a new application of the algorithm used in quantum computers (quantum algorithm), and is expected to contribute to our understanding of important problems such as the time evolution and the phase structure of the early universe in finite density regions, which have been difficult to analyze using conventional methods.

For more details, please see the press release article from Kyoto University at related links.

Many biological time-series data are not stationary, which makes it difficult to analyze the instantaneous phase and amplitude. In the iTHEMS Biology seminar on February 17, I talked about Hilbert transform, which is known as a method to estimate the phase and the amplitude dynamics of nonstationary time-series. First, I explained the mathematical background of the method. Then, I introduced some applications of this method to chronobiology, virus dynamics, and acoustic engineering. In this seminar, there were many questions and comments from audiences. Thank you very much!

On 18th Feb. 2022, Dr. Yuta Sekino gave an excellent introductory talk on Spin transport in ultracold atomic gases. In his talk, we discussed the usefulness of spin transport as a probe for many-body properties in ultracold atoms.
In the first part, we focused on the conductivity of alternating spin current, which includes information on superfluid gap, pseudogap, and topological phase transition. In the latter part, we considered mesoscopic spin transport between two Fermi gases weakly connected with each other. Finally, we discussed similarities of ultracold atoms to neutron star matter.

Reported by Shigehiro Nagataki

On Feb.18, 2022, Dr. Gergely Fejos (Eotvos Lorand Univ., Hungary) gave a talk at the first iTHEMS - R-CCS(FTRT) Joint Seminar. He reported a functional renormalization group study of the three dimensional Ginzburg--Landau potential for the chiral phase transition in three flavor quantum chromodynamics. The order of the phase transition in this system has long been thought to be first-order, but his conclusions suggest the possibility of a second-order phase transition. A lively discussion took place between the speakers and the audience on this interesting result.

Reported by Tetsuo Hatsuda

An online event was held on March 10, 2022 on the theme of the relationship between basic science and society. Sasada san (Mathematician), Yamagiwa san (anthropologist) and Hatsuda san (physicist), moderated by Tsuboi san (artist), had lively discussions on what the "universality" means in natural and social sciences, and also the role of scientists as "catalysts" to link science and society.

The video is available on youtube. Please see the related link.

In this week’s biology seminar, with great honor, we have Prof. Mochizuki to give us an interesting talk on “Independent regulation of multiple checkpoints in cell-cycle network system-Biological function originated in the law of localization-”. He showed us how mathematical analysis about the complex cell cycle networks can provide knowledge on non-trivial behaviors in regularization systems. The transformation from complex cell cycle networks to structural sensitivity matrix is amazing. He and his collaborator found the “buffering structure” which are essential local characters as the origin of biological function. Furthermore, “buffering structure” can generally appear in chemical reaction network including complex formation.
He specially studied the G1-S and G2-M checkpoints in cell cycle. The analyses clarified that, even the two checkpoints are regulated by different protein complexes (Cdc2-Cdc13 and Cdc2-Cig2, respectively) with common species of proteins and activation reactions conform a complicated network, these two complexes are regulated by disjoint sets of reaction parameters in the system. We are looking forward to the further study of comparison with cell cycle experimental data.
Many questions and discussions arose from the audiences. We appreciated very much the time Prof.Mochizuki shared with us.

Reported by Yingying Xu

Title: Merger and post-merger of binary neutron stars with a quark-hadron crossover equation of state
Author: Yong-Jia Huang, Luca Baiotti, Toru Kojo, Kentaro Takami, Hajime Sotani, Hajime Togashi, Tetsuo Hatsuda, Shigehiro Nagataki, Yi-Zhong Fan
arXiv: http://arxiv.org/abs/2203.04528v1

Title: Tunable Dirac Semimetals with Higher-order Fermi Arcs in Kagome Lattices Pd$_3$Pb$_2$X$_2$ (X = S, Se)
Author: Simin Nie, Jia Chen, Changming Yue, Congcong Le, Danwen Yuan, Wei Zhang, Hongming Weng
arXiv: http://arxiv.org/abs/2203.03162v1

Title: Universality of linear perturbations in SU($N$)-natural inflation
Author: Tomohiro Fujita, Kai Murai, Ryo Namba
arXiv: http://arxiv.org/abs/2203.03977v1

Title: New constraints on the neutron-star mass and radius relation from the terrestrial nuclear experiments
Author: Hajime Sotani, Nobuya Nishimura, Tomoya Naito
arXiv: http://arxiv.org/abs/2203.05410v1