Monday, September 27, 16:00- iTHEMS Colloquium
Friday, October 1, 12:30- Coffee Meeting

Dr. Tomoki Ozawa (Visiting Scientist, iTHEMS) writes on the website "SURI-JOSHI" about topological insulators and his research life and daily life. Please see the related link for the article.

Koki Katsuhara (Assistant Professor, Okayama University; at the time: Kobe University), Yuuya Tachiki (Assistant Professor, Tokyo Metropolitan University), Ryosuke Iritani (Research Scientist, iTHEMS; at the time: University of California, Berkeley, University of Exeter) and Atsushi Ushimaru (Professor, Kobe University) performed simulations using an individual-based model and found that in two plant species that share the same species of pollinator and are in competition, evolutionary rescue occurs in which the evolution of higher self-fertilization rates in the rarer species results in an increase in population size, thereby promoting long-term coexistence between the two species.

The results of this study add a new theory to explain why multiple flowering species can coexist in the same place, and also provide a new perspective for the evolution of diverse reproductive strategies in plants. Understanding the mechanisms that create and maintain plant diversity, which supports the basis of terrestrial ecosystems, is essential not only for understanding the origin of biodiversity, but also for forming a sustainable society in harmony with ecosystems, and is an important knowledge in both basic and applied aspects.

For more information, please visit the Okayama University website at the related link.

Yuta Murakami from Tokyo Institute of Technology told us about "High-harmonic generation in strongly correlated systems." High-harmonic generation (HHG) by strong AC electric fields is one of the hottest topics in cond-mat physics. After a brief overview of HHG in various materials such as gasses and semi-conductors and also recent experimental results in Mott insulators, Yuta explained his recent numerical studies on HHG in strongly correlated systems and clarified unique features of HHG arising from the strongly-correlated nature. About 30 people joined the seminar and we enjoyed fruitful discussions during and after the seminar.

Reported by Hidetoshi Taya

Matteo Baggioli (Jiao-Tong U. Shanghai) gave a talk on "Towards a description of amorphous solids and viscoelastic materials using effective field theory and holographic methods." Amorphous and viscoelastic materials appear in many places, not only in scientific problems but also in our daily life. Despite its ubiquity, there are many intriguing phenomena that are not yet understood, in particular, in the non-linear regime. In the talk, Matteo explained his recent attempts to formulate non-linear responses in amorphous and viscoelastic materials based on holographic and effective-field-theory techniques. Matteo also discussed open problems and future directions that we can pursue in the future. There were about 30 participants from various fields of physics, and we had fruitful discussions from a broad point of view during and even after the talk.

Reported by Hidetoshi Taya

Title: On the ease of excitation of black hole ringing: Quantifying the importance of overtones by the excitation factors
Author: Naritaka Oshita
arXiv: http://arxiv.org/abs/2109.09757v1

Title: Effective field theory of fluctuating wall in open systems: from a kink in Josephson junction to general domain wall
Author: Keisuke Fujii, Masaru Hongo
arXiv: http://arxiv.org/abs/2109.10335v1

Title: Persistence of cluster structure in the ground state of $^{11}$B
Author: Naoyuki Itagaki, Tomoya Naito, Yuichi Hirata
arXiv: http://arxiv.org/abs/2109.09957v1

Title: High-dimensional structure learning of sparse vector autoregressive models using fractional marginal pseudo-likelihood
Author: Kimmo Suotsalo, Yingying Xu, Jukka Corander, Johan Pensar
Journal Reference: Stat Comput 31, 73 (2021)
doi: https://doi.org/10.1007/s11222-021-10049-z
arXiv: http://arxiv.org/abs/2011.01484v1

Title: Principal-Axis Analysis of the Eddington Tensor for the Early Post-Bounce Phase of Rotational Core-Collapse Supernovae
Author: Wakana Iwakami, Akira Harada, Hiroki Nagakura, Ryuichiro Akaho, Hirotada Okawa, Shun Furusawa, Hideo Matsufuru, Kohsuke Sumiyoshi, Shoichi Yamada
arXiv: http://arxiv.org/abs/2109.05846v2

Title: Universal relations between the quasinormal modes of neutron star and tidal deformability
Author: Hajime Sotani, Bharat Kumar
arXiv: http://arxiv.org/abs/2109.08145v1

Title: A semi-analytic afterglow with thermal electrons and synchrotron self-Compton emission
Author: Donald C. Warren, Maria Dainotti, Maxim V. Barkov, Bjorn Ahlgren, Hirotaka Ito, Shigehiro Nagataki
arXiv: http://arxiv.org/abs/2109.07687v1

Title: Derivative expansion in the HAL QCD method for a separable potential
Author: Sinya Aoki, Koichi Yazaki
arXiv: http://arxiv.org/abs/2109.07665v1