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23 news in 2025

2025-02-27
Paper of the Week
Week 5, February 2025

Title: Detection of molecular clouds in the PeVatron candidate source LHAASO J0341 $+$ 5258 by the Nobeyama 45-m radio telescope Author: Naomi Tsuji, Shunya Takekawa, Kaya Mori, Alison Mitchell, Shuo Zhang, Priyadarshini Bangale, Stephen DiKerby, Tülün Ergin, Jooyun Woo, Samar Safi-Harb, Shinta Kausya arXiv: 2502.15432
2025-02-25
Hot Topic

Farewell message from Jeffrey Fawcett

Our colleague, Jeffrey Fawcett will move on to a new career as a Chief Scientist at Regional Fish Institute, Ltd. as of March 1st, 2025. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Jeffrey Fawcett: I will be moving to Kyoto to work at a company called Regional Fish from March. I will also most likely have a joint position at Kyoto University at a lab funded by the company. The company was started a few years ago mostly be people from Kyoto University, Graduate School of Agriculture, where I did my study, and specializes in breeding and developing fish and aquatic species using genome editing and various other techniques. My task will mainly be to perform genomic data analysis for the company, although I will also have some freedom to pursue my own research. I am looking forward to the new challenge to utilize my expertise and work for a company whose I mission I can identify with. I have been in iTHEMS for exactly 7 years, which say how much I enjoyed and appreciated the setup of iTHEMS. I remember some people telling me its their first time meeting a biologist, whereas I never imagined I would ever have the opportunity to enjoy talks on pure mathematics and theoretical physics. I would like to thank all the people involved in iTHEMS and hopefully I will be able to visit iTHEMS from time to time and keep up the connection.
2025-02-25
Seminar Report

Visit by ASCENT-6E high school students on January 13, 2025

On Monday, January 13th, 2025, we were glad to receive the visit of 15 high school students (13 female and 2 male) enrolled in the STELLA Program ASCENT-6E of Chiba University. The students, accompanied by the Program Director Prof. Jun Nomura, Prof. Atsushi Tsuji, and Program Coordinators Prof. Qian Wang and Prof. Hina Morishige, were welcome to a one-day workshop organized by iTHEMS members. The workshop consisted of a series of presentations in which iTHEMS members talked about some of the fundamental, yet unresolved, questions about our universe. We covered topics ranging from mathematics, biology, physics, and philosophy of science. The objective was to promote the curiosity of students towards science, using iTHEMS as an example of how scientists from different disciplines may interact and do research together under the same roof. We also took the chance to advertise the different RIKEN programs for young researchers and encouraged the students to follow their dreams of becoming professional scientists. During lunchtime and the interactive sessions, we also enjoyed nice opportunities to converse directly with the students, listen to their particular interests, and answer their questions. This visit by the STELLA program ASCENT-6E students was an invaluable opportunity for us at iTHEMS to understand the current situation of young students, their motivations, and their innovative ideas. For the sake of promoting love for science, inclusivity in academia, and a closer interaction with society, we hope that we can create more bridges between the iTHEMS members and the young students in the future. We are glad that the workshop was a success. Please see the webpage of STELLA Program ASCENT-6E to read some of the comments that students made regarding their visit to iTHEMS. Reported by José Said Gutiérrez-Ortega
2025-02-25
Seminar Report

Theories of Astrophysical Big Bangs 2025 on February 17, 2025

The international workshop “Theories of Astrophysical Big Bangs 2025” was held at RIKEN from February 17 to 19. During the workshop, Daniel Kasen (UC Berkeley), who is currently on sabbatical at RIKEN, delivered a special lecture on supernovae and kilonovae. In addition, 25 invited talks were presented, allowing participants to share the latest advancements in the field of Astrophysical Big Bangs. The workshop also featured 33 poster presentations, showcasing the diverse range of research in the field and fostering extensive discussions among participants. A total of 83 participants from six countries, including Japan, registered for the workshop. This event was supported by the JST ASPIRE project for top scientists: “RIKEN-Berkeley Mathematical Quantum Science Initiative”, which particularly contributed to strengthening research collaboration between RIKEN and UC Berkeley. The workshop is expected to serve as a catalyst for future joint research endeavors. Reported by Shigehiro Nagataki
2025-02-20
Paper of the Week
Week 4, February 2025

Title: Systematic study of the composition of Type I X-ray burst ashes: Neutron star structure v.s. Reaction rate uncertainties Author: Guoqing Zhen, Helei Liu, Akira Dohi, Guoliang Lü, Nobuya Nishimura, Chunhua Zhu, Renxin Xu arXiv: 2502.10992 Title: Chiral symmetry restoration in QC_2D from effective model using the functional renormalization group Author: G. Fejos, D. Suenaga arXiv: 2502.10134 Title: Birational Transformations and 2d (0,2) Quiver Gauge Theories beyond Toric Fano 3-folds Author: Dongwook Ghim, Minsung Kho, Rak-Kyeong Seong arXiv: 2502.08741 Title: Numerical evidence for a CP broken deconfined phase at $θ=π$ in 4D SU(2) Yang-Mills theory through simulations at imaginary $θ$ Author: Mitsuaki Hirasawa, Masazumi Honda, Akira Matsumoto, Jun Nishimura, Atis Yosprakob arXiv: 2502.09115
2025-02-20
Seminar Report

Pebbles in Planet Formation on February 10-13, 2025

From February 10 to 13, the workshop "Pebbles in Planet Formation" featured a diverse range of topics, including dust theory, solar system small body exploration, dust experiments, simulations of planetesimal formation via instabilities, and observations of protoplanetary disks. The program included six keynote talks, 40 contributed talks, and 18 poster presentations. Ample time was allocated for coffee breaks and discussion sessions, fostering in-depth conversations on various topics. In particular, the workshop reaffirmed the importance of collaboration between experimental groups in Germany and experimental and theoretical groups in Japan. As a result, we have established a foundation for ongoing communication and future cooperation. Reported by Misako Tatsuuma
2025-02-13
Paper of the Week
Week 3, February 2025

Title: Physics-Conditioned Diffusion Models for Lattice Gauge Theory Author: Qianteng Zhu, Gert Aarts, Wei Wang, Kai Zhou, Lingxiao Wang arXiv: 2502.05504
2025-02-10
Hot Topic
Farewell message from Nozomi Kakinuma

Our administrative staff member, Nozomi Kakinuma, will be leaving RIKEN on February 14 to return to academic research. We will greatly miss her and wish her all the best in her future endeavors. Here is a message from Nozomi: Since April last year, I have been part of iTHEMS as a staff member in the iTHEMS Promotion Office. However, I have recently decided to pursue a career in research. Through coffee meetings, where researchers passionately discussed their work and explained it in an accessible way, I came to deeply appreciate both the excitement and significance of fundamental research. Inspired by these experiences, I am now committed to dedicating myself to research. I am truly grateful for all the support and guidance I have received. Thank you very much.
2025-02-10
Press Release

Who Is at Higher Risk of Progression from Acute Liver Injury to Acute Liver Failure?

A collaborative research group, including Professor Shingo Iwami (Visiting Scientist, iTHEMS / Professor, Graduate School of Science, Nagoya University), has applied artificial intelligence (AI) technology to clinical research. Through joint research, they discovered that patients with acute liver injury can be classified into three groups based on their treatment response. Furthermore, they successfully developed the world's first AI model capable of predicting which group a patient belongs to using clinical data such as initial blood test results. For more details, please visit Kyushu University’s website via the related links.
2025-02-06
Paper of the Week
Week 2, February 2025

Title: Investigating the Bouncing Barrier with Collision Simulations of Compressed Dust Aggregates Author: Haruto Oshiro, Misako Tatsuuma, Satoshi Okuzumi, Hidekazu Tanaka arXiv: 2502.03107 Title: Renormalization-group approach to the Kohn-Luttinger superconductivity: Amplification of the pairing gap from $\ell^4$ to $\ell$ Author: Yuki Fujimoto arXiv: 2502.01169 Title: $NJ/ψ$ and $Nη_c$ interactions from lattice QCD Author: Yan Lyu, Takumi Doi, Tetsuo Hatsuda, Takuya Sugiura arXiv: 2502.00054 Title: Identification of finite circular metric spaces by magnitude and Riesz energy Author: Hiroki Kodama, Jun O'Hara arXiv: 2408.06091 Title: Computing theta-dependent mass spectrum of the 2-flavor Schwinger model in the Hamiltonian formalism Author: Akira Matsumoto, Etsuko Itou, Yuya Tanizaki arXiv: 2501.18960 Title: Novel Lattice Formulation of 2D Chiral Gauge Theory via Bosonization Author: Okuto Morikawa, Soma Onoda, Hiroshi Suzuki arXiv: 2501.18949 Title: Biological invasion by the cycad-specific scale pest Aulacaspis yasumatsui (Diaspididae) into Cycas revoluta (Cycadaceae) populations on Amami-Oshima and Okinawa-jima, Japan Author: Benjamin E. Deloso, José Said Gutiérrez-Ortega, Jui-Tse Chang, Yasuko Ito-Inaba, Anders J. Lindström, L. Irene Terry, John Donaldson, William Tang, Ronald D. Cave, Jorge Antonio Gómez-Díaz, Vanessa M. Handley, M. Patrick Griffith, Thomas E. Marler Journal Reference: Plant Species Biology doi: https://doi.org/10.1111/1442-1984.12505 Title: Spacetime profile of electromagnetic fields in intermediate-energy heavy-ion collisions Author: Hidetoshi Taya arXiv: 2501.18171
2025-01-31
Seminar Report

Quantum Computation SG Seminar by Suguru Endo on January 28, 2025

In this 2-day lecture, Dr. Endo reviewed quantum error mitigation, which offers a practical approach to reducing errors in noisy intermediate-scale quantum (NISQ) devices without requiring the encoding of qubits. The first day started by discussing the fundamentals of noise modeling in quantum systems, and then we overviewed concrete examples of QEM techniques, including extrapolation, probabilistic error cancellation (PEC), virtual distillation, quantum subspace expansion, and Clifford data regression. After that, the lecturer presented advanced QEM methods, such as the stochastic PEC approach, which mitigates the effects of Lindblad terms in Lindblad master equations and the generalized quantum subspace expansion, which is a unified framework of QEM. In the second day, the lecturer introduced recent research topics including information-theoretic analysis of QEM, connections to non-Markovian dynamics, combination of QEM with quantum error correction toward the early fault-tolerant quantum computing era. The lecture attracted attendees with wide research backgrounds ranging from quantum information to condensed matter, nuclear, and particle physics. Reported by Yuta Sekino
2025-01-30
Paper of the Week
Week 5, January 2025

Title: $Λ$ (1405) in the flavor SU(3) limit using a separable potential in the HAL QCD method Author: Kotaro Murakami, Sinya Aoki arXiv: 2501.17423 Title: Multi-Messenger and Cosmological Constraints on Dark Matter through Two-Fluid Neutron Star Modeling Author: Ankit Kumar, Sudhakantha Girmohanta, Hajime Sotani arXiv: 2501.16829 Title: Left-hand cut and the HAL QCD method Author: Sinya Aoki, Takumi Doi, Yan Lyu arXiv: 2501.16804 Title: Reconstruction of QCD first-order phase transition from neutron star measurements Author: Ronghao Li, Sophia Han, Zidu Lin, Lingxiao Wang, Kai Zhou, Shuzhe Shi arXiv: 2501.15810 Title: Synthesis of a semimetallic Weyl ferromagnet with point Fermi surface Author: Ilya Belopolski, Ryota Watanabe, Yuki Sato, Ryutaro Yoshimi, Minoru Kawamura, Soma Nagahama, Yilin Zhao, Sen Shao, Yuanjun Jin, Yoshihiro Kato, Yoshihiro Okamura, Xiao-Xiao Zhang, Yukako Fujishiro, Youtarou Takahashi, Max Hirschberger, Atsushi Tsukazaki, Kei S. Takahashi, Ching-Kai Chiu, Guoqing Chang, Masashi Kawasaki, Naoto Nagaosa, Yoshinori Tokura Journal Reference: Nature (2025) doi: https://doi.org/10.1038/s41586-024-08330-y Title: Grassmann Tensor Renormalization Group for two-flavor massive Schwinger model with a theta term Author: Hayato Kanno, Shinichiro Akiyama, Kotaro Murakami, Shinji Takeda arXiv: 2501.14086 Title: Pair Correlation of Zeros of the Riemann Zeta Function I: Proportions of Simple Zeros and Critical Zeros Author: Siegfred Alan C. Baluyot, Daniel Alan Goldston, Ade Irma Suriajaya, Caroline L. Turnage-Butterbaugh arXiv: 2501.14545
2025-01-29
Press Release

Make it worth Weyl: engineering the first semimetallic Weyl quantum crystal

An international research team, including Ching-Kai Chiu (Senior Research Scientist, iTHEMS) and led by the Strong Correlation Quantum Transport Laboratory of the RIKEN Center for Emergent Matter Science (CEMS) has achieved a world-first by realizing an ideal Weyl semimetal, marking a major breakthrough in quantum materials research. Weyl fermions emerge as quantum excitations of electrons in crystals and are predicted to exhibit exotic electromagnetic properties. However, previous Weyl materials were often overshadowed by unwanted electronic states, making it difficult to observe pure Weyl fermion behavior. The team successfully engineered an ideal Weyl semimetal by precisely controlling the composition of the topological semiconductor (Cr,Bi)₂Te₃, eliminating irrelevant electronic states. Published in Nature, this work opens new possibilities for terahertz (THz) light devices and next-generation electronics. For more details, please refer to the related link.
2025-01-28
Award

Lingxiao Wang received the “Best ‘Physics for AI’ Paper Award”

Our colleague Lingxiao Wang (Research Scientist, iTHEMS) has received the “Best ‘Physics for AI’ Paper Award” of the Machine Learning and the Physical Sciences Workshop. The winning paper is entitled “Higher-order cumulants in diffusion models”. Congratulations, Lingxiao!
2025-01-24
Hot Topic

Farewell message from Liang Zhang

Our colleague, Liang Zhang, has returned to the Shanghai Institute of Applied Physics at the University of Chinese Academy of Sciences to complete his PhD thesis. We will all miss him and wish him the very best of luck in successfully defending his thesis ! Here is a message from Liang Zhang: I joined iTHEMS in January 2023 as a joint student and completed my two-year journey here in January 2025. I initially joined iTHEMS to study lattice QCD and the HAL QCD method, and I am deeply grateful to Hatsuda-san and Doi-san for guiding me into this fascinating field. However, I soon realized that my experience at iTHEMS extended far beyond my original purpose. For example I had a discussion with Namba san on chiral symmetry breaking which is studied in both particle physics and cosmology. It left an immediate impression that physics is so universal other than reading such sentences in textbooks. And the interdisciplinary energy at iTHEMS constantly amazed me. When I first came here I always struggled to pinpoint people’s major. In some seminars, theoretical physicists gave a biology talk (like Christy)! I vaguely feel like there is a group theory for nature which can be expressed to different representations, biological, mathematical, physical, etc. Is this what the “i” in iTHEMS means? At last I would like to thank everyone in iTHEMS again for my two-year experience here. This experience gives me a great impulse to expand the possibilities of my future research life. iTHEMS’s uniqueness lies in its boundless possibilities. And I dearly hope our paths will cross again!
2025-01-23
Paper of the Week
Week 4, January 2025

Title: Numerical simulation of fractional topological charge in $SU(N)$ gauge theory coupled with $\mathbb{Z}_N$ 2-form gauge fields Author: Motokazu Abe, Okuto Morikawa arXiv: 2501.11438 Title: On the connected sums of the $(2,1)$ -cable of the figure eight knot Author: Yoshihiro Fukumoto, Masaki Taniguchi arXiv: 2501.07910 Title: Lifetime measurement of the muonic atom of enriched Si isotopes Author: R. Mizuno, M. Niikura, S. Akamatsu, T. Fujiie, K. Ishida, T. Ito, T. Kikuchi, T. Matsuzaki, F. Minato, J. Murata, T. Naito, K. Shimomura, S. Takeshita, I. Umegaki, Y. Yamaguchi arXiv: 2501.05897 Title: On the slice-torus invariant $q_M$ from $\mathbb{Z}_2$ -equivariant Seiberg--Witten Floer cohomology Author: Nobuo Iida, Taketo Sano, Kouki Sato, Masaki Taniguchi arXiv: 2501.07788 Title: Tridiagonal Hamiltonians modeling the density of states of the Double-Scaled SYK model Author: Pratik Nandy Journal Reference: JHEP 01 (2025) 072 doi: https://doi.org/10.1007/JHEP01(2025)072 arXiv: 2410.07847
2025-01-17
Hot Topic

Farewell message from Lucy McNeill

Our colleague Lucy McNeill has moved on to a new career as a Hakubi Assistant Professor at The Hakubi Center for Advanced Research, Kyoto University as of January 16, 2025. We all will miss her and wish her the best of luck in her latest endeavor. Here is a message from Lucy McNeill: During my 1 year at iTHEMS as a postdoctoral researcher, I was presented with opportunities to further both my own research and professional development at every turn. I am especially grateful for iTHEMS directors and colleagues' support in starting the "asymptotics in astrophysics" iTHEMS study group, ample chances to travel abroad to share my work, and the frequent international workshops organised at iTHEMS. In particular, workshops co-hosted with RIKEN-Berkeley left this lasting impression on me; that new stellar astrophysics and supernova physics paradigms are creatively and efficiently conceived when physicists, mathematicians and data scientists join forces to solve longstanding astrophysical puzzles. iTHEMS is such a special place where those necessary first interactions are regularly facilitated, and I am sad to leave. But... "I'll be back"!
2025-01-16
Paper of the Week
Week 3, January 2025

Title: Direct Monte Carlo computation of the 't~Hooft partition function Author: Okuto Morikawa, Hiroshi Suzuki arXiv: 2501.07042 Title: Impact of dark matter distribution on neutron star properties Author: Ankit Kumar, Hajime Sotani arXiv: 2501.07052 Title: Physics-Driven Learning for Inverse Problems in Quantum Chromodynamics Author: Gert Aarts, Kenji Fukushima, Tetsuo Hatsuda, Andreas Ipp, Shuzhe Shi, Lingxiao Wang, Kai Zhou Journal Reference: Nature Reviews Physics (2025) doi: https://doi.org/10.1038/s42254-024-00798-x arXiv: 2501.05580
2025-01-10
Hot Topic

Farewell message from Yantao Wu

Our colleague Yantao Wu will move on to a new career as a faculty member at Institute of Physics, Chinese Academy of Sciences as of January 10, 2025. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Yantao Wu: I joined iTHEMS in June 2021 as a RIKEN-Berkeley fellow, and have stayed here for three years and a half now. iTHEMS is a precious rare place in the academic world, where there seems to be no responsibility, no one telling you what to do, and infinite space for travel; where there seems to be a curious mind on every subject and every question ought to be asked. The interdisciplinary nature of the group has forever left an imprint on me, and I will always remember the vivid biological facts and mathematical tricks that I have learned here. Entering as a condensed matter physicist and leaving as a condensed matter physicist, my heart will always have a spot for the particle theory which I have learned from here. It has been an unexpected, yet very pleasant mix. Sadly, it appears that every gathering ends somewhere, and I need to leave this warm and protective bubble to a new place, to really enter the grown world of independent research and start my own group. iTHEMS will always remain as a source of lasting encouragement. I will move to the Institute of Physics, Chinese Academy of Sciences in Beijing to start a faculty position. If you ever want to visit, please let me know you are from iTHEMS and I will make you a cup of tea (amidst taking you to the great wall and covering your travel costs.)
2025-01-10
Press Release

Discovery of Measurement-Induced Spectral Phase Transition in Quantum Systems

A collaborative research team, including Ryusuke Hamazaki (Senior Research Scientist, iTHEMS / RIKEN Hakubi Team Leader, Nonequilibrium Quantum Statistical Mechanics RIKEN Hakubi Research Team, RIKEN Cluster for Pioneering Research (CPR)), has discovered a spectral phase transition in quantum systems under measurement. This research is expected to bridge the gap between two seemingly distinct phenomena: the recently emerging field of “measurement-induced phase transitions in nonequilibrium quantum systems" and the long-studied "phase transitions in equilibrium quantum systems." By discovering the analogy between these transitions, this work paves the way for a deeper understanding of quantum many-body systems. Using a method known as Lyapunov analysis, the team demonstrated the existence of spectral phase transitions in quantum systems under measurement. Furthermore, they found that the critical point of these spectral phase transitions coincides with the critical point of entanglement transitions. For more details, please refer to the related link.
2025-01-09
Paper of the Week
Week 2, January 2025

Title: Imaginary Hamiltonian variational ansatz for combinatorial optimization problems Author: Xiaoyang Wang, Yahui Chai, Xu Feng, Yibin Guo, Karl Jansen, Cenk Tüysüz arXiv: 2408.09083 Title: GRB Redshift Classifier to Follow-up High-Redshift GRBs Using Supervised Machine Learning Author: Maria Giovanna Dainotti, Shubham Bhardwaj, Christopher Cook, Joshua Ange, Nishan Lamichhane, Malgorzata Bogdan, Monnie McGee, Pavel Nadolsky, Milind Sarkar, Agnieszka Pollo, Shigehiro Nagataki arXiv: 2408.08763 Title: Isosceles trapezoids of unit area with vertices in sets of infinite planar measure Author: Junnosuke Koizumi arXiv: 2501.01914 Title: From planar to annular to toroidal bracket polynomials for pseudo knots and links Author: Ioannis Diamantis, Sofia Lambropoulou, Sonia Mahmoudi arXiv: 2501.00736 Title: Monte Carlo simulation of the $SU(2)/\mathbb{Z}_2$ Yang--Mills theory Author: Motokazu Abe, Okuto Morikawa, Hiroshi Suzuki arXiv: 2501.00286 Title: Deep learning for exploring hadron-hadron interactions Author: Lingxiao Wang arXiv: 2501.00374
2025-01-02
Paper of the Week
Week 1, January 2025

Title: QCD sum rule approach to Okamoto-Nolen-Schiffer anomaly Author: Hiroyuki Sagawa, Tomoya Naito, Xavier Roca-Maza, Tetsuo Hatsuda arXiv: 2412.19851 Title: Jackiw-Teitelboim Gravity and Lorentzian Quantum Cosmology Author: Masazumi Honda, Hiroki Matsui, Kota Numajiri, Kazumasa Okabayashi arXiv: 2412.20398 Title: Phase and equation of state of finite density QC $_2$ D at lower temperature Author: Etsuko Itou, Kei Iida, Kotaro Murakami, Daiki Suenaga arXiv: 2412.18825 Title: Violation of Parity and Flavor Symmetries in a Nambu-Jona-Lasinio Model Author: Yukimi Goto, Tohru Koma arXiv: 2412.19244
2025-01-02
Press Release

Ancient DNA unlocks new understanding of migrations in the first millennium AD

A new study published in Nature reveals waves of human migration across Europe during the first millennium AD using a more precise method of analysing ancestry with ancient DNA. Led by Leo Speidel, ECL Unit Leader at RIKEN iTHEMS, formally a Sir Henry Wellcome postdoctoral researcher at the Francis Crick Institute and UCL, alongside Pontus Skoglund at the Francis Crick Institute, this study reports a new data analysis method called Twigstats. Applied to over 1500 ancient genomes, the new approach reveals previously unknown details of migrations in Europe during the first millennium AD (year 1 to 1000), encompassing the Iron Age, the fall of the Roman Empire, the early medieval ‘Migration Period’ and the Viking Age. The new approach can be applied to populations across the world and may enable researcher to reveal more missing pieces of the puzzle in future. Please refer to the press release by the Francis Crick Institute for further details.

23 news in 2025