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Japan’s High Energy Accelerator Research Organization (KEK) has been steadily improving the performance of its flagship electron-positron collider, SuperKEKB, since it produced its first electron-positron collisions in April 2018.  At 20:34 on 15th June 2020, SuperKEKB achieved the world’s highest instantaneous luminosity for a colliding-beam accelerator, setting a record of 2.22×1034 cm-2 s-1. Previously, the KEKB collider, which was SuperKEKB’s predecessor and was operated by KEK from 1999 to 2010, had achieved the world’s highest luminosity, reaching 2.11×1034 cm-2 s-1. KEKB’s record …

A group of researchers including scientists from the RIKEN Nishina Center for Accelerator-Based Science, University of Tokyo, Nagoya University, and the Japan Atomic Energy Agency (JAEA) used the spin-polarized Relativistic Heavy Ion Collider at Brookhaven National Laboratory in the United States to show that in polarized proton-proton collisions, the neutral pions in the very forward area of collisions—where direct interactions involving quarks and gluons are not applicable—still have a large degree of left-right asymmetry. This finding suggests that the previous …

Scientists from the international XENON collaboration, an international experimental group including the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), University of Tokyo; the Institute for Cosmic Ray Research (ICRR), University of Tokyo; the Institute for Space-Earth Environmental Research (ISEE), Nagoya University; the Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University; and the Graduate School of Science, Kobe University, announced today that data from their XENON1T, the world’s most sensitive dark …

Prototype Schwarzschild–Couder Telescope (pSCT, see Fig. 1), one of prototype telescopes developed for the Cherenkov Telescope Array (CTA) project, observed the Crab Nebula and successfully detected very-high-energy gamma rays from the object with a statistical significance of 8.3σ (Figs. 2–4). The viability of two new technologies used in pSCT, the Schwarzschild–Couder optical system with a large field of view of 8 degrees and a small camera pixel size of 6 mm realized by using silicone photomultipliers (SiPMs), have been proved …

The Division of Experimental Studies in KMI seeks to fill a full-time, non-tenure-track, Associate Professor position. The successful candidate is expected to participate in a flavor physics experiment using a high-energy accelerator, together with researchers at KMI, and also promote collaborative research with other groups in KMI, such as theoretical particle physics. For more details, please read KMI-2020-2-E  

The Division of Experimental Studies in KMI seeks to fill a full-time, non-tenure-track, Associate Professor position. The successful candidate is expected to participate in a flavor physics experiment using a high-energy accelerator, together with researchers at KMI, and also promote collaborative research with other groups in KMI, such as theoretical particle physics. For more details, please read KMI-2020-2-E  

Division for Theoretical Studies in KMI seeks to fill a full-time, non-tenure-track, Associate Professor position. The successful candidate will engage in research on the theory of elementary particle physics, cosmology, or their interdisciplinary field in order to shed light on dark universe. For more details, please read KMI-2020-1-E　    

Prof. Junji Hisano has been appointed as the new Director of the Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI) on April 1st, 2020. KMI was founded in April 2010 after the Novel prize award in physics to Profs. Kobayashi and Maskawa for their discovery of origin of broken symmetry. Since then, KMI has been conducting theoretical, experimental and observational studies of elementary particles and the universe under the leadership of Profs. Kobayashi and Maskawa. This year, our …

  The Belle II experiment—an international collaboration of physicists searching for signs of undiscovered particles—has published the experiment’s first results in a paper selected as an Editors’ Suggestion in Physical Review Letters. The results offer physicists new clues in their hunt for dark matter, a substance believed to make up some 85% of the universe. The Belle II experiment, which operates at the SuperKEKB electron-positron collider in Tsukuba, Japan, searched for a hypothetical new particle called the Z’ that may …

Novel mechanism to avoid theoretical bound on kaon rare decays Researchers try to revisit a theoretical bound, which is based on symmetries, between the charged and neutral kaon rare decays into the pion and neutrinos. Last September, KOTO experiment searching for neutral kaon rare decay reported events with an unexpected rate, which is much bigger than the standard model predictions. So far, KOTO experiment has not claimed that these events are the rare kaon decay signals. On the other hand, …