October 11, 2024
Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI)
The University of Tokyo Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI) Professor Shigeki Matsumoto has been named one of the recipients of this year’s Particle Physics Medal, awarded by the Japan Particle and Nuclear Theory Forum.
Matsumoto is receiving the medal as part of a three-person team, and his co-recipients are also affiliates of Kavli IPMU: High Energy Accelerator Research Organization (KEK) Professor and Kavli IPMU Senior Fellow Mihoko Nojiri, and Nagoya University Graduate School of Science Professor and Kavli IPMU Visiting Senior Scientist Junji Hisano.
The researchers received their medals during a ceremony at the 79th Annual Meeting of the Japan Physical Society, hosted at Hokkaido University between September 16 – 19.
The Particle Physics Medals has been awarded annually since 2000, and was established to further inspire research in particle physics, nuclear physics and related fields. Members of the Japan Physical Society’s Particle Theory Committee select the recipients. The researchers they choose are ones who have made significant contributions to particle theory and its surrounded fields. By recognizing the efforts by these researchers, the society aims to encourage the next generation of researchers to pursue their own original research.
Past recipients include the late Jiro Maki, who theorized that neutrinos could oscillate, and the late Toichiro Kinoshita, who was a world leader in quantum electrodynamics calculations. Kavli IPMU Visiting Senior Scientist Tsutomu Yanagida also received the medal in 2020.
Matsumoto is being recognized for his contributions to the discovery of threshold resonance effects in dark matter annihilation. He co-wrote a paper in 2003, “Unitarity and higher-order corrections in neutralino dark matter annihilation into two photons” that was published in Physical Review D, and another paper in 2004 titled, “Explosive Dark Matter Annihilation” that was published in Physical Review Letters.
“It has been theoretically proven that the dark matter annihilation cross section can be amplified by more than 4 orders of magnitude, if the cross section is non-perturbatively enhanced by a short-range gravitational force. This is called the Sommerfeld enhancement. It does not need to be said that uncovering the nature of dark matter is the biggest question facing researchers studying the universe and its elementary particles. Weakly interacting massive particle (WIMP) is one candidate predicted by supersymmetry and multi-dimensional theories, and has long been the center of attention in many theoretical and experimental studies. But interpreting the data from these experiments, which currently include direct, indirect and accelerator-based searches of particles such as the higgsino and wino, is impossible without considering the Sommerfeld enhancement. This emphasizes how important it is to further study this effect in more detail. Of course, dark matter may turn out to be something that is not a WIMP, but what is certain is that WIMPs will have a significant effect on future research projects for another few decades. Even if dark matter is not a WIMP, other areas of research, including calculating freeze-out in the early universe and its disappearance in galaxies, also need to take the Sommerfeld effect into consideration. This paper has been cited more than 650 times, a sign of its impact in the field. Given its difficult theoretical and technical challenges, the committee has decided that this achievement deserves to be recognized with this year’s Particle Physics Medal,” said the Particle Theory Committee.
Matsumoto believes his paper has made such an impact in the research community because of the many people who helped shape it.
“This research is one I started in 2000 together with Nagoya University Professor and Kavli IPMU Visiting Senior Scientist Junji Hisano, and KEK Professor and Kavli IPMU Senior Fellow Mihoko Nojiri. We found that when dark matter has a force exerted on it, properties such as its annihilation cross section are greatly enhanced. Our work has been applied to other particle physics projects and collaborations with other researchers including Kyoto University’s Masato Senami, Kavli IPMU’s Satoshi Shirai, and The University of Chicago’s Keisuke Harigaya to name a few.
“In 2011, after the Higgs boson discovery, I worked with Kavli IPMU and Shanghai Jiao Tong University’s Tsutomu Yanagida and Kavli IPMU Visiting Scientist Masahiro Ibe to construct the Pure Gravitation Mediation. We found the supersymmetric model based on the anomaly transfer mediation mechanism to be the most promising model in modern physics.
“At the same time, many other researchers and research groups came to the same conclusion as us, and we were lucky that so many people could validate the results from our paper.
“Further, while this research was carried out by myself and my colleagues, it would not have materialized without the discussions I had had with other two researchers. First is my supervisor and Okayama University Project Professor Motohiko Yoshimura. When I was a graduate student at Tohoku University, I was studying the environmental effects on elementary processes. Professor Yoshimura taught me how to take on new problems. He taught me the importance of starting with the first principle and from there to build discussions, and he taught me that to develop an effective theory, sometimes it helps to simplify the problem by integrating out the lighter particles, not the heavy ones.
“The second researcher was another lecturer at Tohoku University during my graduate studies, Professor Yukinari Sumino. Professor Sumino had spent many years researching threshold singularities, an area which became the foundation of this research I am being recognized for. He was a thesis supervisor of my friend, and I had a chance to join their discussion and learn physics related to the singularities. Without the discussions I had with these researchers, I never would have been able to write these papers, and I am forever grateful,” said Matsumoto.
About Shigeki Matsumoto
Education and Experience
2000 Doctor of Science In Physics, Graduate School of Science, Tohoku University
2000 Research Fellow, Japan Society for the Promotion of Science
2003 Researcher, Institute for Cosmic Ray Research, The University of Tokyo
2005 Researcher, High Energy Accelerator Research Organization
2007 Assistant Professor, Faculty of Science, Tohoku University
2008 Associate Professor, Graduate School of Science and Engineering, University of Toyama
2010 – 2015 Project Associate Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU,
WPI), The University of Tokyo
2015 – 2019 Associate Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The
University of Tokyo
2017 – 2022 Principal Investigator, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The
University of Tokyo
2019 - Professor, Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The University
of Tokyo
Awards
2000 Aoba Society for the Promotion of Science Award
2007 Particle Physics Medal: Young Scientist Award in Theoretical Particle Physics
Related links
List of Particle Physics Medal recipients (Japanese)
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Kavli IPMU’s Tsutomu Yanagida Awarded 20th Particle Physics Medal of Japan (November 11, 2020)