ニュース
170件のニュース / 2023年

20230504
今週の論文Week 1, May 2023
Title: Nonlinear chiral kinetic theory Author: Kazuya Mameda arXiv: http://arxiv.org/abs/2305.02134v1 Title: Spatial deformation of manybody quantum chaotic systems and quantum information scrambling Author: Kanato Goto, Taozhi Guo, Tomoki Nosaka, Masahiro Nozaki, Shinsei Ryu, Kotaro Tamaoka arXiv: http://arxiv.org/abs/2305.01019v1

20230502
ホットトピックRIKEN iTHEMS signed a new MoU with Lawrence Berkeley National Laboratory (LBNL)
Reiner Kruecken (Director of the Nuclear Science Division of LBNL) and Tetsuo Hatsuda (Director of RIKEN iTHEMS) are the principal coordinators for LBNL and RIKEN iTHEMS, respectively, for this MoU [1]. The photo was taken in front of the desk of Ernest Lawrence [2], which is preserved at LBNL.

20230428
今週の注目人物Selfintroduction: Rongyang Sun
My name is Rongyang Sun. I joined RIKEN in October 2021 as a Postdoctoral Researcher in RCCS and RQC. Now, I am very glad to hold this concurrent position in iTHEMS. As a fullstack researcher in computational quantum manybody physics, my ultimate goal is to understand the fantabulous nature of quantum manybody systems by taking advantage of modern supercomputing systems and quantum computers. Towards this goal, I am developing advanced tensor network algorithms, maintaining highperformance tensor computing software, and applying these tools to the study of strongly correlated systems like interacting electrons and frustrated spins. Meanwhile, I am also exploring the possibility of utilizing nearterm quantum computers to arrive at the same destination.

20230428
今週の注目人物Selfintroduction: Tomonori Shirakawa
My name is Tomonori Shirakawa. I joined iTHEMS as a Senior Research Scientist in April 2023. I am interested in quantum manybody phenomena in condensed matter physics. To better understand quantum manybody phenomena, I have been working with various numerical methods. In particular, I have recently been exploring more efficient ways to solve quantum manybody problems using quantumclassical hybrid algorithms, quantum algorithms, and tensor network methods.

20230427
セミナーレポートiTHEMS Biology Seminar by Mr. Naoki Konno on April 20, 2023
In April 20, Mr Naoki Konno (University of Tokyo) gave a fantastic talk about the machine leaning method for the prediction of evolution. The talk was entitled, “Machine learning predicts biological system evolution by gene gains and losses”. To my knowledge, this study using genome data of ~3000 species is one of few seminal attempts to theoretically predict longterm and systemlevel evolution. The seminar by Konno san was very clear and we understood the predictability of the proposed framework, called “Evodictor”. In the beginning of the talk, he kindly explained the theoretical basis about phylogenetic tree estimation and machine learning for nonspecialists for which we could enjoy and learn from his seminar a lot. Thank you, Konnosan for the great talk!! Reported by Gen Kurosawa

20230424
リサーチニュースRIKEN Research: Quantum ‘magic’ could help explain the origin of spacetime
A quantum property dubbed ‘magic’ could be the key to explaining how space and time emerged, a new mathematical analysis by three RIKEN physicists suggests. It’s hard to conceive of anything more basic than the fabric of spacetime that underpins the Universe, but theoretical physicists have been questioning this assumption. “Physicists have long been fascinated about the possibility that space and time are not fundamental, but rather are derived from something deeper,” says Kanato Goto of the RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS). To read more, please visit the related link.

20230424
セミナーレポートABBLiTHEMS Joint Astro Seminar by Dr. Kumiko Kotera on April 18, 2023
We are living exciting times: we are now able to probe the most violent events of the Universe with diverse messengers (cosmic rays, neutrinos, photons and gravitational waves). One challenge to complete the multimessenger picture resides in the highest energies, as no ultrahigh energy neutrinos have been observed yet. This challenge could be undertaken by the GRAND (Giant Radio Array for Neutrino Detection) project, which aims at detecting ultrahigh energy particles, with a colossal array of 200'000 antennas over 200'000 km2, split into ~20 subarrays of ~10'000 km2 deployed worldwide. In this talk, Kumiko Kotera presented preliminary designs and simulation results, plans for the ongoing, staged approach to construction, and the rich research program made possible by the proposed sensitivity and angular resolution. Reported by Shigehiro Nagataki

20230420
今週の論文Week 4, April 2023
Title: Investigating Time Evolution of Thermal Emission from the Putative Neutron Star in SN 1987A for 50+ Years Author: Akira Dohi, Emanuele Greco, Shigehiro Nagataki, Masaomi Ono, Marco Miceli, Salvatore Orlando, Barbara Olmi arXiv: http://arxiv.org/abs/2304.08418v1 Title: The Impacts of NeutronStar Structure and Base Heating on Type I XRay Bursts and Code Comparison Author: Guoqing Zhen, Guoliang Lv, Helei Liu, Akira Dohi, Bobuya Nishimura, Chunhua Zhu, Liyu Song, Weiyang Wang, Renxin Xu arXiv: http://arxiv.org/abs/2304.07197v1 Title: Plausible presence of new state in neutron stars with masses above $0.98M_{\rm TOV}$ Author: MingZhe Han, YongJia Huang, ShaoPeng Tang, YiZhong Fan doi: https://doi.org/10.1016/j.scib.2023.04.007 arXiv: http://arxiv.org/abs/2207.13613v2

20230417
リサーチニュースRIKEN Research: Gravitational waves could indicate transition to strange quark matter
Telltale signatures in gravitationalwave signals from merging neutron stars should reveal what happens to matter at the extreme pressures generated during such mergers, calculations by RIKEN researchers predict [1]. If you took some water and compressed it with a piston, it would shrink as the molecules get pushed closer together. If you continued ramping up the pressure, you’d reach a point where the atoms collapse and form an ultradense soup of neutrons and protons. The only place in the Universe where this happens is neutron stars, the collapsed remnants of burnedout stars, and it produces mindboggling densities—one teaspoon of such material weighs several hundred billion kilograms. But what would happen if you continued to increase the pressure still further? Not even astrophysicists know the answer to that. To read more, please visit the related link.

20230413
今週の論文Week 3, April 2023
Title: Observing Supernova Neutrino Light Curves with SuperKamiokande. IV. Development of SPECIAL BLEND: a New Public Analysis Code for Supernova Neutrinos Author: Akira Harada, Yudai Suwa, Masayuki Harada, Yusuke Koshio, Masamitsu Mori, Fumi Nakanishi, Ken'ichiro Nakazato, Kohsuke Sumiyoshi, Roger A. Wendell arXiv: http://arxiv.org/abs/2304.05437v1 Title: From diffeomorphisms to exotic phenomena in small 4manifolds Author: Hokuto Konno, Abhishek Mallick, Masaki Taniguchi arXiv: http://arxiv.org/abs/2304.05997v1 Title: GammaRay Emission in the Seyfert Galaxy NGC 4151: Investigating the Role of Jet and Coronal Activities Author: Yoshiyuki Inoue, Dmitry Khangulyan arXiv: http://arxiv.org/abs/2304.04138v1

20230413
セミナーレポートSeminar, "Introduction to the Renormalization group method as a powerful reduction method of dynamics" by Dr. Teiji Kunihiro on April 10, 2023
In April 10, Dr Teiji Kunihiro (Prof Emeritus, Kyoto Univ) gave an introductory talk about the renormalization group method, entitled “Introduction to the Renormalization group method as a powerful reduction method of dynamics.” In fact, this talk was the first seminar at our new seminar room #359 with the splendid blackboard in RIKEN Wako Campus. The talk by Kunihirosan using the blackboard was very very clear, and we can understand the power of the Renormalization group method and its applicability [1]. The talk was also delivered via Zoom (i.e. ~35 participants in total), and there were lively discussions between the lecturer and the audience. After the talk, he kindly shared his lecture note with us so that we can take advantage of it. Thank you, Kunihirosan for the wonderful talk!! Reported by Gen Kurosawa

20230411
セミナーレポートLabTheory Standing Talks #1 by Dr. Hideshi Ooka on March 16, 2023
The first LabTheory standing talk took place on March 16th, 2023, inviting Hideshi Ooka from CSRS (Riken Center for Sustainable Resource Science). He picked up the chemical process of making hydrogen from water as the subject. By design, the event is organized in a very informal setting."I was glad that the speaker prepared very few slides and all the slides were simple because it gave the audience an opportunity to ask many random questions in all sorts of direction," one of the participants, Catherine Beauchemin says. As she says, "in this light and flexible format, it is the audience that can decide what aspects are more interesting for them and ask more questions about it," there have been many questions asked and discussions followed. The event appears to be fruitful for the speaker too; "I will share the comment with my colleagues, as I believe it is a chance to advance the level of chemistry in our lab, " Hideshi Ooka concludes. Reported by Tsukasa Tada

20230410
今週の注目人物Selfintroduction: Seishiro Ono
My name is Seishiro Ono. I received my Ph.D. from the University of Tokyo in March 2023, and then I joined RIKEN iTHEMS in April 2023. My research interests lie in quantum condensed matter physics. I have been fascinated by the diversity of this field, and I am eager to understand the various phenomena from a unified point of view. I am currently investigating a unified understanding of superconductivity based on symmetry and topology. In addition, I have recently become interested in experimental signatures of topological nature, applications of machine learning to materials science, and quantum simulation of strongly correlated systems.

20230407
セミナーレポートiTHEMS Biology Seminar by Dr. Yohei Nakayama on March 30, 2023
On March 30th, Dr. Nakayama talked about F1ATPase from both experimental and theoretical aspects. In the introduction, he reviewed biological molecular motors and experimental facts. Then he introduced a Langevin model for the kinetics of F1 and explained how a specific case of the model fits the previous experiments. In the main part, he told us about new experimental results, relation to the theoretical model, and theoretical prediction based on the model. We thank Dr. Nakayama for giving us an exciting presentation. Reported by Kyosuke Adachi

20230407
今週の注目人物Selfintroduction: Zixia Wei
My name is Zixia Wei, and I got my Ph.D. from Yukawa Institute, Kyoto University in March 2023. I work on many different aspects of the AdS/CFT correspondence. The AdS/CFT correspondence relates a gravitational theory to a nongravitational theory in a lowerdimensional system. Recently, I am interested in studying statistical physics with the help of the AdS/CFT correspondence. Thermal states in nongravitational systems, which are often the targets of statistical physics, are related to black holes via the AdS/CFT correspondence. Obvious observations in black holes are sometimes nontrivial when translated back to statistical systems. I am working on making nontrivial conjectures in general statistical systems by considering black holes and then trying to prove them back in statistical systems.

20230406
今週の論文Week 2, April 2023
Title: AtiyahHirzebruch spectral sequence for topological insulators and superconductors: $E_2$ pages for 1651 magnetic space groups Author: Ken Shiozaki, Seishiro Ono arXiv: http://arxiv.org/abs/2304.01827v1 Title: Frobenius algebras associated with the $α$induction for equivariantly braided tensor categories Author: Mizuki Oikawa arXiv: http://arxiv.org/abs/2303.11845v1 Title: Involutions, links, and Floer cohomologies Author: Hokuto Konno, Jin Miyazawa, Masaki Taniguchi arXiv: http://arxiv.org/abs/2304.01115v1

20230406
今週の注目人物Selfintroduction: CheYu Chen
Hi, my name is CheYu Chen, a Taiwanese researcher, joining RIKEN iTHEMS as an SPDR in April 2023. I got my Ph.D. in Physics from National Taiwan University in 2019. After my graduation, I stayed as a postdoc at LeCosPANTU (20192020) and then became an AS postdoc at the Institute of Physics, Academia Sinica (20202023), before coming to RIKEN. My interest is mainly in gravitational physics, including modified gravity and the phenomenological aspects of quantum gravity. In particular, I'm currently working on using stateoftheart black hole observations to test general relativity (GR), or even to probe putative nonGR physics. The direct detection of gravitational waves emitted from binary black hole mergers, and the images of supermassive black holes, have ushered in a completely new era in which directly probing spacetimes near black holes becomes possible. There are several interesting nonGR physics, some of which could even be motivated by quantum gravitational effects. These nonGR physics could induce nontrivial or even unique imprints on gravitational waveforms and black hole images, and hence can possibly be tested in the future. A better understanding of this topic can tell us how well GR describes such extreme spacetime regimes, and if it were to be modified, which direction is more observationally preferred. I'm looking forward to the fruitful discussions with the iTHEMS members in the future.

20230405
今週の注目人物Selfintroduction: Tomoya Nagai
My name is Tomoya Nagai. I joined as a coordinator in April 2023. I started working after getting the Ph.D. in astrophysics and have worked in science communication, R&D strategy development, research funding and R&D management. Until March 2023, I worked at KEK and Kobe University, where I was manager of research projects using the supercomputers “Fugaku". I will do my best to help you in your research.

20230405
今週の注目人物Selfintroduction: Tingyu Zhang
My name is Tingyu Zhang, and I joined iTHEMS as a junior research associate in April 2023. Now I am involved in a PhD program in physics at the University of Tokyo. I mainly focus on the study of quantum manybody systems and nonequilibrium physics. Specifically I’m now studying the transport phenomena in cold atomic systems, through Green’s function methods and the perturbation theory. I’m looking forward to discussing physics with other researchers in the future.

20230331
プレスリリース取引ネットワークの相関テンソルによる暗号資産の価格バーストの予測 ―安心して使える暗号資産とデジタル経済の実現にむけて―
暗号資産は、デジタル経済の時代に欠かせない存在となりつつあります。理研と京大の共同研究では、ネットワークの数理科学を駆使することによって、マネーロンダリングや詐欺などの異常事象の検出、価格バーストの予知を行う理論的研究に取り組んでいます。池田裕一（京都大学総合生存学館教授）、アビジット・チャクラボルティ（同特定助教/iTHEMS客員研究員）、初田哲男（理化学研究所数理創造プログラムディレクター）の研究グループは、暗号資産の取引ネットワークに対応する相関テンソルのスペクトルを解析する新規手法を開発して、相関テンソルの最大特異値が暗号資産の価格と有意な負の相関を示すことを発見しました。この発見を用いて、価格バーストの早期指標を提供できる見通しを得ました。 詳細は、関連リンクから京都大学のプレスリリース記事をご覧ください。

20230331
受賞情報Dr. Thomas Hitchcock received the "Best English Presentation Award" of Ecological Society of Japan
Thomas Hitchcock (SPDR, iTHEMS) received the "Best English Presentation Award" at the 70th Annual meeting of the Ecological Society of Japan (ESJ) held on March 2023 for his presentation on "Paternal genome elimination promotes altruism in viscous populations". Congratulations, Thomas!

20230331
受賞情報Dr. José Said GutiérrezOrtega received the "Excellent English Presentation Award" of Ecological Society of Japan
José Said GutiérrezOrtega (SPDR, iTHEMS) received the "Excellent English Presentation Award" at the 70th Annual meeting of the Ecological Society of Japan (ESJ) held on March 2023 for his presentation on "Disparate patterns of niche evolution in the diversification of the Neotropical cycad genus Ceratozamia (Zamiaceae)". Congratulations, José !

20230331
ホットトピックMessages from Tetsuo Hatsuda (March 31, 2023)
Dear iTHEMS members Today is the last day of FY2022. I would like to express my deepest gratitude to all of you for your efforts in overcoming the pandemic this year and continuing your research activities. I would also like to thank the following people who physically have left or are leaving iTHEMS for their great contributions to iTHEMS during FY2022. Bon Voyage! Etsuko Itou, Masaki Taniguchi, Naritaka Oshita, Takuya Sugiura, Yuki Yazaki, Matthias Berwein, Akira Matsumoto, Chris Bourne, Michiya Mori, Shou Yoshikawa, Don Warren, Shunsuke Kobayashi, Hiroshi Yokota, Gilberto Nakamura, Kazumi Kuwata. With best regards, Tetsuo Hatsuda

20230329
受賞情報The paper coauthored by Dr. Ryosuke Iritani has been selected as "Editors' Choice" of OIKOS
The paper entitled "Species interactions and diversity: a unified framework using Hill numbers" coauthored by Dr. Ryosuke Iritani (Research Scientist, iTHEMS) has been selected as the Editors' Choice in OIKOS. Congratulations!

20230329
書籍物性物理とトポロジー  非可換幾何学の視点から
窪田陽介 [著]

20230328
ホットトピックFarewell message from Dr. Euki YAZAKI
Our colleague Euki YAZAKI will move to the Research Center for Advanced Analysis, National Agriculture and Food Research Organization as a Research Scientist from April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Euki YAZAKI: As I prepare to leave after three wonderful years at RIKEN, I would like to take this opportunity to express my gratitude to all of you. It has been an honor to work with such a wonderful group of theoretical and mathematical scientists and I have learned so much from each and every one of you. I would like to thank all my colleagues who have supported me during my time at iTHEMS. Your expertise and enthusiasm have been invaluable, and I am grateful for the time I have spent with you. I would also like to thank the staff at iTHEMS support for their many supports. Although I will be moving on to new adventures, I hope to continue to enjoy good research with iTHEMS members in the future.

20230327
セミナーレポートiTHEMS Biology Seminar by Dr. Midori Tuda on March 23, 2023
Dr. Tuda gave us a very wellprepared, clear and interesting presentation about her group's current research. Her work is primarily experimental, while iTHEMS Biology members' work is primarily theoretical, which could create interesting opportunities. We found many common interest between her research and that of iTHEMS Biology members, such as niche divergence under a changing climate (GutiérrezOrtega), sex ratio of offsprings (Hitchcock), and species coexistence/competition (Iritani). This gave rise to many interesting questions, comments and exchanges. We hope to continue conversation. Reported by Catherine Beauchemin

20230323
今週の論文Week 4, March 2023
Title: Gradientflowed order parameter for spontaneous gauge symmetry breaking Author: Kengo Kikuchi, Kenji Nishiwaki, Kinya Oda arXiv: http://arxiv.org/abs/2303.10841v1 Title: Toric nonarchimedean $μ$entropy and thermodynamical structure Author: Eiji Inoue arXiv: http://arxiv.org/abs/2303.09090v1

20230323
ホットトピックFarewell message from Dr. Akira Matsumoto
Our colleague Akira Matsumoto will move to the Yukawa Institute for Theoretical Physics, Kyoto University as a ProgramSpecific Researcher from April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Akira Matsumoto: I have been a member of iTHEMS for almost one year, which is the first opportunity for me to work as a postdoc. In spite of the difficult situation of COVID19, I was able to enjoy research activity thanks to a good environment of iTHEMS and great effort by assistants. It is interesting to join seminars and discussions freely with researchers from various fields. I would like to thank all the iTHEMS members for giving me nice experiences. I plan to be a visiting scientist of iTHEMS after leaving RIKEN. I am very happy to keep in contact with iTHEMS members and looking forward to collaboration in the future.

20230322
受賞情報Dr. Yalong Cao received FY2022 RIKEN Excellent Achievement Award
Yalong Cao (Research Scientist, iTHEMS) received the FY2022 RIKEN BAIHO Award (梅峰賞) (RIKEN Excellent Achievement Award" for his excellent achievement on "Study of DonaldsonThomas Invariants on CalabiYau 4folds". Congratulations!

20230316
今週の論文Week 3, March 2023
Title: Coupled Hénon Map, Part II: Doubly and Singly Folded Horseshoes in Four Dimensions Author: Jizhou Li, Keisuke Fujioka, Akira Shudo arXiv: http://arxiv.org/abs/2303.06824v1 Title: Coupled Hénon Map, Part I: Topological Horseshoes and Uniform Hyperbolicity Author: Keisuke Fujioka, Ryota Kogawa, Jizhou Li, Akira Shudo arXiv: http://arxiv.org/abs/2303.05769v1

20230316
ホットトピックFarewell message from Dr. Hiroshi Yokota
Our colleague Hiroshi Yokota has moved to the Graduate School of Human and Environmental Studies, Kyoto University as a CREST postdoctoral researcher from March 1, 2023. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Hiroshi Yokota: I had worked at iTHEMS as a postdoctoral researcher for almost 4 years. I would like to thank all the iTHEMS members for the valuable discussions on their researches including my own research. Moreover, in iTHEMS, I had very good opportunities to attend the exciting seminars and colloquiums which gave me brilliant ideas from the various fields: physics, biology, mathematics and information. I enjoyed the discussions, the seminars and the colloquiums in iTHEMS. I also would like to thank all assistants who gave us the comfortable research environment. Fortunately, I am allowed to be the visiting scientist in iTHEMS. I hope to discuss with iTHEMS members in future also.

20230315
ホットトピックFarewell message from Dr. Naritaka Oshita
Our colleague Naritaka Oshita will move to the Kyoto University as a Hakubi assistant professor from April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Naritaka Oshita: I enjoyed studying gravity and black holes while being a part of iTHEMS and participating in some iTHEMS events and activities. As of the end of this March, it has been almost two years since I started my second postdoc at iTHEMS as an SPDR fellow in 2021 April. From 2023 April, I will be a Hakubi assistant professor at Kyoto University and will start my exciting new research to understand the mystery of gravity. I enjoyed discussing with many iTHEMS members who are working on physics, biology, mathematics, (quantum) information theory, etc. I thank all faculties, researchers, and students at iTHEMS for having exciting discussions with me! iTHEMS assistants have been contributing to this group to improve the research environment at iTHEMS and they kindly helped me a lot when I needed their help and was in trouble. I appreciate all the assistants at iTHEMS for their support and for having fun conversations! Again, thank you to all members at iTHEMS for everything! I will still be a part of iTHEMS as a visiting researcher. I hope I can have exciting discussions and conversations with you in the future. See you again!

20230315
リサーチニュースRIKEN NEWS: 基礎科学特別研究員インタビュー② 38歳でたどり着いた数学者としての大きな第一歩
佐野 岳人 基礎科学特別研究員のインタビュー記事が、理研の研究紹介ページ「クローズアップ科学道 2023」に掲載されました。 理研には、国際的に活躍する研究者の育成を目指し、若手研究者が自ら設定した研究課題を自由な発想で主体的に研究できる「基礎科学特別研究員制度」があります。1989年に始まったこの制度は、現在公募中の2024年度採用で35回目となります。これを機に、各分野で活躍する先輩たちと現役にインタビューしました。第2回は、数理創造プログラム（iTHEMS）の佐野 岳人 基礎科学特別研究員です。 続きは、関連リンクをご覧ください。

20230313
ホットトピックFarewell message from Dr. Masaki Taniguchi
Our colleague Masaki Taniguchi will move to the Kyoto University as an assistant professor from April 1st. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Masaki Taniguchi: I'd like to thank the program director and assistants for many helpful supports over these three years and also many research members for discussing with me. I spent three years in iTHEMS as a mathematical researcher(SPDR). During the three years, I could concentrate on doing my research and communicating with researchers in other fields. In particular, I had been attending a weekly seminar focusing on interactions between math and physics. It was a valuable experience to feel various viewpoints from physics. Also, I got a chance to give a presentation at an event of RIKEN for high school or junior high school students. In my final year, I was chosen as a research member of a program at MSRI and spent four months at Berkeley to communicate with many researchers in my field. I could also invite several researchers to the math seminar and had good opportunities to promote research. I appreciate a good environment in iTHEMS so that I could have these experiences. From this April, I’ll be an assistant professor at Kyoto University. But, I still have several collaborators in iTHEMS, so I’d like to continue discussing with many researchers in iTHEMS as a visiting researcher.

20230313
ホットトピックFarewell message from Dr. Etsuko Itou
Our colleague Etsuko Itou will move to the Yukawa Institute for Theoretical Physics, Kyoto University as an associate professor from April 1st. We all will miss her and wish her the best of luck in her latest endeavor. Here is a message from Etsuko Itou : I worked at iTHEMS for almost a year as a senior research scientist. I had the opportunity to discuss researches with people from various backgrounds, go on a short trip to Kawagoe, and give presentations at interdisciplinary research meetings, which was a valuable experience for me. I would also like to thank my assistants and PR staff for their support! I will be a visiting scientist of iTHEMS next year. I look forward to working with you again.

20230313
ホットトピックInterdisciplinary Science Conference in Okinawa (ISCO 2023) on February 27, 2023
On Feb.27 (Mon)March 3 (Fri), ISCO 2023 (Interdisciplinary Science Conference in Okinawa 2023  Physics and Mathematics meet Medical Science ) was held at OIST (Okinawa Institute of Science and Technology). The conference was cohosted by RIKEN iTHEMS, Kavli IPMU and OIST, with 135 participants inside and outside Japan. This was the first inperson conference held in OIST after the Covid19 pandemic. There were 28 invited talks and 9 contributed talks. From RIKEN iTHEMS, Gordon Baym, Catherine Beauchemin, Gen Kurosawa, Hiro Nagataki, Hidetoshi Nishimori, Tomoki Ozawa, and Takashi Tsuboi gave scientific talks, and Tetsuo Hatsuda gave a closing remark. The purpose of ISCO 2023 was to bring together leading researchers in the fields of physics, astrophysics, mathematics, data science, life science, environmental science, and medical science, and to discuss the latest advancements in their respective fields. In addition to the presentations held at the OIST auditorium, a tour inside the OIST campus as well as a special lecture about Sharks by Dr. K. Sato at Churaumi Aquarium were held. Participants have intensive discussions beyond the disciplines at the plenary, poster, and lunch sessions. Some of the presentation slides can be downloaded from the ISCO 2023 webpage.

20230313
ホットトピック理化学研究所奈良女子大学理学部合同 ダイバーシティ推進ワークショップが3月7日に開催されました
3月7日と3月8日の2日間、奈良女子大学理学部の2回生、3回生、4回生（合計16名）が理研の川上研究室、侯研究室、iTHEMS, RIBF施設、宮脇研究室を訪問しました。それぞれの研究室で、最先端研究の一端に触れるとともに、初日夕方からの理研研究者との交流会では、より深く研究内容について質問したり、研究者の日常を知る機会も設けられました。また、数学、物理学、生物学、環境化学など奈良女子大学理学部の異なるコースの学生たちが、学年を越えて交流する機会にもなりました。 このダイバーシティ推進活動は、奈良女子大学理学部と理研iTHEMSが共同で推進するリケジョ育成事業の一環として、奈良女子大学での連続講義とセットで行われているもので、次年度以降も継続する予定です。

20230313
リサーチニュースRIKEN Research: Explanation found for puzzling observation of Shiba states in superconductors
The origin of a mysterious experimental observation in a superconductor with a magnetic impurity sitting on top of it has been revealed in a theoretical study by a RIKEN researcher and a collaborator. This could help realize a robust quantum state residing in a superconductor that may find application in quantum computers. Superconductors conduct electricity without any resistance because electrons in them form pairs that have an energy gap. But placing a magnetic atom on top of a superconductor creates a new state in this energy gap as a result of the atom’s magnetism interacting with the superconductor’s paired electrons. Known as the Yu–Shiba–Rusinov state, or Shiba state for short, this state has been attracting a lot of interest because it could shed light on the emergence of a special state in a topological superconductor called the Majorana zero mode, which is promising for realizing faulttolerant quantum computing. To read more, please visit the related link.

20230313
セミナーレポートABBLiTHEMS Joint Astro Seminar by Dr. Ellis Owen on March 10, 2023
Ultra highenergy (UHE) cosmic rays (CRs) from distant sources interact with intergalactic radiation fields, leading to their spallation and attenuation through photohadronic processes. Their deflection and diffusion in large scale intergalactic magnetic fields (IGMFs), in particular those associated with Mpcscale structures, alter the cumulative cooling and interactions of a CR ensemble to modify their spectral shape and composition observed on Earth. In this talk, Ellis Owen demonstrated the extent to which IGMFs can affect observed UHE CRs, and showed that source population models are degenerate with IGMF properties. Interpretation of observations, including the endorsement or rejection of any particular UHE CR source classes, needs careful consideration of the structural properties and evolution of IGMFs. Future observations providing tighter constraints on IGMF properties will significantly improve confidence in assessing UHE CR sources and their intrinsic CR production properties. Reported by Shigehiro Nagataki

20230309
今週の論文Week 2, March 2023
Title: Empirical neutron star mass formula based on experimental observables Author: Hajime Sotani, Tomoya Naito arXiv: http://arxiv.org/abs/2303.03631v1 Title: On the regularity conditions for holographic nonlinear responses: electric conductivity and friction coefficient Author: Shuta Ishigaki, Shin Nakamura, Kazuaki Takasan arXiv: http://arxiv.org/abs/2303.02633v1 Title: Neutron star massradius constraints using the highfrequency QPOs of GRB 200415A Author: H. Sotani, K. D. Kokkotas, N. Stergioulas arXiv: http://arxiv.org/abs/2303.03150v1

20230307
セミナーレポートiTHEMS Biology Seminar by Dr. Adrian GonzalezCasanova on January 19, 2023
We had the pleasure to have Dr. Adrián GonzálezCasanova (Neyman Visiting Assistant Professor, The University of California, Berkeley, USA / Associate Professor, National Autonomous University of Mexico, Mexico) in our Biology seminar of January 19th, 2023. He presented us a talk consisting of two sections. First, he explained to us the basis of the coalescent theory: a model that depicts how alleles within a population relate each other until reaching a common ancestor. Second, he presented us how the coalescent theory can be used to explain and predict the behavior of one of the most intriguing experiments in evolutionary biology: the Lenski experiment. The Lenski experiment consists of a daily cultivation of E. coli; each day's culture is grown from a population cultivated the previous day. This, way, after thousand generations, the experiment has shown that the fitness increase of individuals is decelerating, but it doesn't decrease or even reach a plateau. Dr. GonzálezCasanova presented us some ideas of how we can model the underlying biological processes behind the experiment while considering other noisy processes such as epistasis or clonal interference, and thus better understand how evolution occurs. Reported by José Said GutiérrezOrtega

20230303
セミナーレポートQuantum Matter Seminar by Dr. YungYeh Chang on March 2, 2023
On March 2nd, 2023, the iTHEMS Quantum Matter Seminar was held online, featuring a talk on "Topological Kondo Superconductors" by YungYeh Chang, a postdoctoral researcher at the National Center for Theoretical Sciences and National Yang Ming Chiao Tung University in Taiwan. YungYeh Chang began by introducing Kondo lattice and heavy fermion compound. Interestingly, superconductivity can emerge in this compound. Then, including topology, he proposed a realization of a 2D timereversal symmetric superconductor in a class of Kondo lattice materials. The proposed system involves the oddparity Kondo hybridization, which mediates ferromagnetic spinspin coupling and leads to spintriplet resonantvalencebond (tRVB) pairing between local moments. The speaker explained that spintriplet p±p' wave topological superconductivity is reached when the Kondo effect coexists with tRVB. By using the mean field theory to generate an effective free fermion (BdG) Hamiltonian, the topological nature was identified by the nontrivial topological invariant and the chiral Majorana modes at edges. The results on the superconducting transition temperature, Kondo coherent scale, and onset temperature of Kondo hybridization were discussed, which not only qualitatively but also quantitatively agree with the observations for UTe2. In summary, the iTHEMS Quantum Matter Seminar on "Topological Kondo Superconductors," presented by YungYeh Chang, provided an insightful discussion on the study of topological superconductors in Kondo lattice materials. The attendees had the opportunity to ask questions and engage in discussions with the speaker, making it an interactive and informative seminar. Reported by ChenHsuan Hsu (Academia Sinica, Taiwan) and ChingKai Chiu

20230302
今週の論文Week 1, March 2023
Title: On the Zeeman Effect in MagneticallyArrested Disks Author: Yoshiyuki Inoue arXiv: http://arxiv.org/abs/2302.14403v1 Title: Electricfield driven nonequilibrium phase transitions in AdS/CFT Author: Daisuke Endo, Yuichi Fukazawa, Masataka Matsumoto, Shin Nakamura arXiv: http://arxiv.org/abs/2302.13535v1

20230223
今週の論文Week 4, February 2023
Title: Color superconductivity on the lattice  analytic predictions from QCD in a small box Author: Takeru Yokota, Yuta Ito, Hideo Matsufuru, Yusuke Namekawa, Jun Nishimura, Asato Tsuchiya, Shoichiro Tsutsui arXiv: http://arxiv.org/abs/2302.11273v1 Title: From Entropy to Echoes: Counting the quasinormal modes and the quantum limit of silence Author: Naritaka Oshita, Niayesh Afshordi arXiv: http://arxiv.org/abs/2302.08964v1 Title: A simple method for multibody wave function of ground and lowlying excited states using deep neural network Author: Tomoya Naito, Hisashi Naito, Koji Hashimoto arXiv: http://arxiv.org/abs/2302.08965v1 Title: Scrambling and Recovery of Quantum Information in Inhomogeneous Quenches in Twodimensional Conformal Field Theories Author: Kanato Goto, Masahiro Nozaki, Shinsei Ryu, Kotaro Tamaoka, Mao Tian Tan arXiv: http://arxiv.org/abs/2302.08009v1 Title: Effects of Coulomb and isospin symmetry breaking interactions on neutronskin thickness Author: Tomoya Naito, Gianluca Colò, Haozhao Liang, Xavier RocaMaza, Hiroyuki Sagawa arXiv: http://arxiv.org/abs/2302.08421v1

20230220
セミナーレポートDMWG Seminar by Dr. Jowett Chan on February 9, 2023
Dark matter (DM) of our Universe could be categorized into three types: cold DM (CDM), warm DM (WDM), or fuzzy DM (FDM) depending on its mass. CDM is the most wellstudied one with its success in largescale structure formations. However, as studies proceed, some problems arise in such models: observations of smallstructure would not match the predictions of CDM structures in simulations. For example, observations of Milky Way satellites indicate the existence of the central core while simulations predict cuspy structures at the center. The feature could be welldescribed by considering FDM of m~O(1e20) eV or below. The unique point of FDM is that the mass of the particle becomes a unique parameter for calculation. In numerical simulations of FDM halos, we can see the formation of cores in the Hubble time (i.e. the age of the Universe) and relaxations of radial structures. As the test particle mass gets larger, coreformation time becomes longer. One possible caveat for FDM models is the socalled "diversity problem". Our satellite galaxies show diversity in their core structures, while FDM predicts a single scale for core size which is determined by the particle mass. It can be understood by considering nonlinear processes of mergers, the diversity could be generated. Mergers could also be responsible for structures at outer radii, such as the density profile proportional to the inverse cubic of the radius. In order to overcome the numerical difficulties and proceed, GPUaccelerated adaptive mesh code is now being intensively invented. We should see fantastic structures of FDM halos in the near future! Reported by Nagisa Hiroshima

20230216
今週の論文Week 3, February 2023
Title: Demographic history and species delimitation of three Zamia species (Zamiaceae) in southeastern Mexico: Z. katzeriana is not a product of hybridization Author: José Said GutiérrezOrtega, Miguel Angel PérezFarrera, Sergio Lopez, Andrew P. Vovides Journal Reference: Botanical Journal of the Linnean Society, boac062 (2023) doi: https://doi.org/10.1093/botlinnean/boac062 Title: Perturbative analysis of the WessZumino flow Author: Daisuke Kadoh, Kengo Kikuchi, Naoya Ukita arXiv: http://arxiv.org/abs/2302.06955v1 Title: BCSBCS crossover between atomic and molecular superfluids in a BoseFermi mixture Author: Yixin Guo, Hiroyuki Tajima, Tetsuo Hatsuda, Haozhao Liang arXiv: http://arxiv.org/abs/2302.04617v1 Title: Doubly charmed tetraquark $T^+_{cc}$ from Lattice QCD near Physical Point Author: Yan Lyu, Sinya Aoki, Takumi Doi, Tetsuo Hatsuda, Yoichi Ikeda, Jie Meng arXiv: http://arxiv.org/abs/2302.04505v1

20230216
セミナーレポートQuantum Matter Seminar by Dr. Chang PoYao on February 9, 2023
Please enter the seminar report here!On February 13, 2023, Assistant Professor PoYao Chang of the Department of Physics at National Tsing Hua University in Taiwan gave an online seminar entitled "Entanglement in nonHermitian quantum systems and nonunitary conformal field theories." In the seminar, Professor Chang began by discussing the motivation for studying nonHermitian systems, such as open quantum systems and those with imaginary self energy induced by interaction or disorder. He then introduced the basic concepts of entanglement entropy, arguing that while the quantity is defined through the ground state, it can be used to characterize the entire system similarly to how Boltzmann's thermal entropy characterizes a classical system. In particular, it can be used to characterize topological systems with anyons. Although general nonHermitian systems have complex eigenvalues, he focused on systems that preserve parity and timereversal (PT) symmetry, so that all of the eigenvalues must be real in order to determine the ground state and the entanglement entropy. He showed that in a nonHermitian model, the entropy is negative and corresponds to the negative central charge, which uniquely characterizes conformal field theories (CFTs). As the main result of his recent work, Professor Chang proposed a generic entanglement entropy to characterize nonHermitian systems and showed how it could be used to correctly obtain the entanglement properties of several nonHermitian systems, such as the nonHermitian SuSchriefferHeeger (SSH) model, the qdeformed XXZ model with imaginary boundary terms, and the AffleckKennedyLiebTasaki (AKLT) model, using numerically extracted central charges. In conclusion, Professor Chang's seminar provided valuable insights into the field of entanglement in nonHermitian quantum systems and nonunitary conformal field theories. The seminar was wellreceived by the audience, who appreciated the clarity of the presentation and the relevance of the research topic. Reported by ChenHsuan Hsu (Academia Sinica, Taiwan) and ChingKai Chiu

20230210
セミナーレポートSuper smash problems workshop 3 on January 2527, 2023
From January 25th to 27th, we organized the third Super Smash Problems (SSP) workshop in Kobe. This time we had Kyosuke Adachi (BDR/iTHEMS SPDR) presenting challenging problems he faced in his work. Two main topics were intensively discussed in the workshop. One of them was concerning the generalization of entropyproduction in information thermodynamics. Entropy production can be regarded as a measure of irreversibility of stochastic processes. In other words, irreversibility necessarily comes with positive entropy production. We discussed various systems in biology, physics, and astrophysics that may be relevant to irreversible stochastic systems, like cell growth, formation of phylogenetic trees, machinelearning process, and how universe emerges. Second topic was about phaseseparation. The theory of phaseseparation has a rich mathematical structure: we explored methods with which we can computationally efficiently construct convexhull of a given function. Also, because various systems exhibit phaseseparation, we discussed the potential for which the method can be applied to other systems, including formation of stars. The threeday discussion did not allow us to reach solid conclusion though, we found it very fun and stimulating that mathematics can explain parts of our world that are seemingly totally different. We will continue discussing the problems and hopefully provide you all an update for something resulting. We the organizers sincerely appreciate the audience who attended Adachisan’s introductory lecture and subsequent discussion; and of course, Adachisan for the effort, time, and passion for the SSP workshop. We believe this was a short but very inspiring opportunity. Thank you so much! On behalf, Ryosuke Iritani Reported by Ryosuke Iritani

20230209
今週の論文Week 2, February 2023
Title: Brueckner $G$matrix approach to twodimensional Fermi gases with the finiterange attractive interaction Author: Hikaru Sakakibara, Hiroyuki Tajima, Haozhao Liang arXiv: http://arxiv.org/abs/2302.03446v1 Title: Nuclear response to dark matter signals in Ge and Xe oddmass targets Author: M. M. Saez, O. Civitarese, T. Tarutina, K. Fushimi arXiv: http://arxiv.org/abs/2302.00879v1 Title: Robust Perfect Adaptation of Reaction Fluxes Ensured by Network Topology Author: Yuji Hirono, Hyukpyo Hong, Jae Kyoung Kim arXiv: http://arxiv.org/abs/2302.01270v1
170件のニュース / 2023年