Featured News
Farewell message from Dr. Jason Chang
Our colleague Jason Chang moves on to a new carrier at LinkedIn as of November 14th. We all will miss him and wish him the best of luck in his latest endeavor. Here is a message from Jason:
2021-11-16
Can social issues be solved by mathematical science? -attempts and challenges
On Oct.26, the symposium "Can social issues be solved by mathematical science? -attempts and challenges" was held under the leadership of Takashi Sakajo (Kyoto Univ.) and Shingo Iwami (Nagoya Univ.) who are also iTHEMS colleagues. The symposium was held in a hybrid matter with more than 220 participants. After the presentations on various approaches to bridge the academia and industry, there were lively discussions on how to cross the valley between the mathematical science and social needs.
2021-11-04
Shigefumi Mori will be awarded the Order of Culture
We are very happy to hear that Shigefumi Mori, Director-General and Distinguished Professor, KUIAS and Senior Advisor of RIKEN iTHEMS, will be awarded the Order of Culture in recognition of his “outstanding achievements in mathematics, especially in algebraic geometry, in creating Mori Theory, a theory of minimal models of algebraic varieties, which has had a significant impact on a wide range of fields in the mathematical sciences, and for his outstanding contributions to the development of this field”. Mori-san’s field of expertise is mathematics, especially algebraic geometry. He was awarded the Fields Prize at the International Congress of Mathematicians in 1990 for his great work on the classification problem of algebraic varieties, a central theme in algebraic geometry, and has continued to vigorously lead research in related areas.
2021-10-28
Prof. Motoko Kotani was elected as the next president of the International Science Council
Prof. Motoko Kotani (Senior Visiting Scientist, iTHEMS) was elected as the next President-elect of the International Science Council (ISC) at the ISC General Assembly held on October 14, 2012. The term of office is for three years starting in 2024. To read more, please see the related link (in Japanese).
2021-10-25
Increased number of drought-responsive genes in a tropical rainforest tree, Shorea leprosula (Dipterocarpaceae)
A collaborative research group including Dr. Jeffrey Fawcett (Senior Research Scientist, iTHEMS) has sequenced the genome of a tropical tree species, Shorea leprosula (Dipterocarpaceae), which is important for the global environment and as an imported timber. Although the trees grow in tropical East Asia, which is blessed with abundant rainfall, they unexpectedly showed an increase in drought-responsive genes, revealing the importance of rare droughts in the tropics. Global environmental change is exacerbating large-scale drought associated with El Niño Southern Oscillations (ENSO) in the tropics, and it is expected that the results of this study will be applied toward sustainable forestry and tropical rainforest conservation. For more information, please visit the Yokohama City University website.
2021-10-20
Mathematics and Physics: Topology, Insulators and My Research Life
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.
2021-09-22
A New Mechanism to Explain Multispecies Coexistence in Plants - Evolutionary Rescue Caused by the Evolution of Self-Fertilization before Flowering
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.
2021-09-17
Supercomputer Predicts Fascinating New Particle Charmed Di-Omega - A new page toward solving the puzzle of the 6-quark states has been added -
An international collaboration including Takuya Sugiura (Postdoctoral Researcher, iTHEMS) , Tetsuo Hatsuda (Program Director, iTHEMS), and Takumi Doi (Senior Research Scientist, Quantum Hadron Physics Laboratory, RNC) has theoretically predicted the existence of a new particle called Charmed Di-Omega which consists of six charm quarks. To read more, please see the related link (in Japanese).
2021-08-31
RIKEN-Vancouver Joint Workshop on Quantum Computing was held on August 24-25, 2021
RIKEN-Vancouver Joint Workshop on Quantum Computing was held online on August 24-25. The main aim of this workshop is that the quantum people in RIKEN (iTHEMS and RQC) and Vancouver (Quantum BC) get together online to discuss scientific activities and explore future collaborations. There were altogether 164 registrations (90 from Japan, 62 from Canada and 12 from other countries). 12 scientific talks were presented together with 3 introduction to iTHEMS, RQC and Quantum BC. From iTHEMS, Jason Chang, Etsuko Itou, and Takumi Doi gave talks respectively on the Schroedinger equation, the U(1) gauge theory and combinatorial optimization. After each session, there were one-hour breakout sessions, so that people can ask further questions to the speakers, which worked very well. The workshop was an excellent first step toward a close tie between RIKEN quantum activities and Vancouver quantum activities.
2021-08-27
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.
2021-08-23
Videos
Interdisciplinary Theoretical and Mathematical Sciences Program (iTHEMS) is an international research program at RIKEN. It facilitates close collaborations among researchers from different disciplines in theoretical, mathematical and computational sciences. The ultimate goal of iTHEMS is to unravel the mystery of the Universe, matter, and life, as well as to solve key problems in modern society through interdisciplinary approaches.
Program Director: Dr. Tetsuo Hatsuda
Upcoming Events
Generalized Bernoulli process and computation of proportional areas for Venn diagram
December 8 at 16:00 - 18:00, 2021
Dr. Ryosuke Iritani (Research Scientist, iTHEMS)
*For detailed information about the seminar, please refer to the email.
Venue: via Zoom
Event Official Language: English
Selective inference for testing trees and edges in hierarchical clustering and phylogeny
December 9 at 10:00 - 11:00, 2021
Prof. Hidetoshi Shimodaira (Professor, Graduate School of Informatics, Kyoto University / Team Leader, Mathematical Statistics Team, RIKEN Center for Advanced Intelligence Project (AIP))
Bootstrap resampling is quite useful for computing “confidence values” or “p-values” of trees and edges. However, they are biased and may lead to false positives (too many wrong discoveries) or false negatives (too few correct discoveries) depending on the “curvature” of the boundary surface of a hypothesis region in the data space. In addition, we face the issue of selection bias because we tend to use the dataset twice for hypothesis selection and its evaluation. I will explain these two types of bias and show methods to adjust the confidence values.
Venue: via Zoom
Event Official Language: English
Magnetic field dependence of neutrino-driven core-collapse supernova models
December 10 at 14:00 - 15:00, 2021
Prof. Jin Matsumoto (Assistant Professor, Graduate School of Science and Technology Keio Institute of Pure and Applied Sciences, Keio University)
Massive stars can explode and release huge energy (typically 10^51 erg) at the end of their life. It is one of the most energetic explosions in the Universe and is called a core-collapse supernova. The impact of the magnetic field on the explosion mechanisms of the core-collapse supernova is a long-standing mystery. Recently, we have updated our neutrino-radiation-hydrodynamics supernova code (3DnSNe, Takiwaki et al. 2016) to include magnetohydrodynamics (MHD). Using this code, we have performed three-dimensional MHD simulations for the evolution of non-rotating stellar cores focusing on the difference in the magnetic field of the progenitors. Initially, 20 and 27 solar mass pre-supernova progenitors are threaded by only the poloidal component of the magnetic field, which strength is 10^10 (weak) or 10^12 (strong) G. We find that the neutrino-driven explosion occurs in both the weak and strong magnetic field models. The neutrino heating is the main driver for the explosion in our models, whereas the strong magnetic field slightly supports the explosion. In my talk, I will introduce the details of this mechanism.
Venue: via Zoom
Event Official Language: English
The long-lived particle search of the FASER experiment
December 15 at 17:00 - 18:00, 2021
Prof. Hidetoshi Otono (Assistant Professor, Research Center for Advanced Particle Physics, Kyushu University)
*For detailed information about the seminar, please refer to the email.
Venue: via Zoom
Event Official Language: English
Opportunities
Seeking a Kyoto University Program-Specific Assistant Professor (female)
Deadline: December 24, 2021
Kyoto University Program-Specific Assistant Professor (female), one position. Seeking a female Program-Specific Assistant Professor who will work for the collaboration between the Kyoto University MAthematics-based Creation of Science (MACS) Program and RIKEN iTHEMS. During her term, she will also serve as a Visiting Scientist at RIKEN iTHEMS.
Seeking a few Postdoctoral Researchers (W21169)
Deadline: Open until filled
Postdoctoral Researcher, a few positions. In particular, we welcome applications from young researchers who are interested in exploring theories of quantum gravity in a broad sense. Currently, Senior Research Scientist Yuki Yokokura is affiliated with iTHEMS, and we expect young researchers with complementary and unique expertise, who are willing to pursue their own ambitious motivation and create synergy among the members.
Seeking a few Postdoctoral Researchers (RIKEN-Berkeley Fellow associated with N3AS) (W21157)
Deadline: Open until filled
Postdoctoral Researcher (RIKEN-Berkeley Fellow associated with N3AS), a few positions. Theoretical works associated with neutrino physics, nucleosynthesis, dense matter and neutron stars, dark matter, astrophysical simulations and related fields.
Seeking a few Postdoctoral Researchers (W21158)
Deadline: Open until filled
Postdoctoral Researcher, a few positions. In particular, the successful applicant(s) are expected to spend at least 50% of their time working with Dr. Ryosuke Iritani carrying out interdisciplinary research addressing fundamental questions in population genetics, phylogenetics, and bioinformatics, by using mathematical and theoretical approach in dynamical systems, stochastic process, statistical physics, and/or information theory. Applicants are expected to have a considerable expertise in those theories.
Seeking a Female Research Scientist or a Female Senior Research Scientist (W21071)
Deadline: Open until filled
Female Research Scientist or Female Senior Research Scientist, a few positions. Seeking a female researcher or a female senior researcher to conduct theoretical research in the fields of natural sciences, mathematical sciences, or humanities and social sciences.
Latest News
2021-12-02
Week 1, December 2021
Title: Flavor number dependence of QCD at finite density by the complex Langevin method Author: Yusuke Namekawa, Yuhma Asano, Yuta Ito, Takashi Kaneko, Hideo Matsufuru, Jun Nishimura, Asato Tsuchiya, Shoichiro Tsutsui, Takeru Yokota arXiv: http://arxiv.org/abs/2112.00150v1 Title: Emergence of the rho resonance from the HAL QCD potential Author: Yutaro Akahoshi, Sinya Aoki, Takumi Doi arXiv: http://arxiv.org/abs/2111.15138v1 Title: Color superconductivity in a small box: a complex Langevin study Author: Shoichiro Tsutsui, Yuhma Asano, Yuta Ito, Hideo Matsufuru, Yusuke Namekawa, Jun Nishimura, Asato Tsuchiya, Takeru Yokota arXiv: http://arxiv.org/abs/2111.15095v1 Title: Perturbative predictions for color superconductivity on the lattice Author: Takeru Yokota, Yuhma Asano, Yuta Ito, Hideo Matsufuru, Yusuke Namekawa, Jun Nishimura, Asato Tsuchiya, Shoichiro Tsutsui arXiv: http://arxiv.org/abs/2111.14578v1 Title: QHC21 equation of state of neutron star matter -- in light of 2021 NICER data Author: Toru Kojo, Gordon Baym, Tetsuo Hatsuda arXiv: http://arxiv.org/abs/2111.11919v1 Title: Flux tube profiles in two-color QCD at low temperature and high density Author: Katsuya Ishiguro, Kei Iida, Etsuko Itou arXiv: http://arxiv.org/abs/2111.13067v1
2021-12-02
Events for the 2nd week of December 2021
Wednesday, December 8, 16:00– 18:00 iTHEMS Math Seminar Thursday, December 9, 10:00– 11:00 iTHEMS Biology Seminar Friday, December 10, 12:30- Coffee Meeting
2021-12-01
ABBL/iTHEMS Astro Seminar by Dr. Hirotaka Yoshino on November 12, 2021
Dr. Yoshino gave us a talk on his recent work on axions around rotating black holes. He showed results of his numerical simulations of so-called “superradiant instability” in which an axion field around a rotating black hole extracts the energy of the black hole. These results suggest that every astrophysical black hole is expected to wear a cloud of the axion. Reported by Akira Mizuta (ABBL, RIKEN)