MSRI holds a semester program “Microlocal Analysis” in fall 2019. I fortunately attend this program while my stay at University California Berkeley (UCB) via iTHEMS-UCB math young visiting scholar program. There were two conferences on microlocal analysis in the third week of October.
From October 14 to 18, there was a conference entitled “Recent Development in Microlocal Analysis”. It consists of 18 talks on various kinds of topics on microlocal analysis by specialists from all over the world. They contain some topics which is very closely related to my research works, such as observability and semiclassical measure.
In October 19 and 20, there was a conference entitled “Microlocal Analysis and Spectral Theory: A Conference in Honor of Richard Melrose”. Richard Burt Melrose is an Australian mathematician who is famous for his broad research on microlocal analysis and geometry. The speakers include two fields medalists, Terence Tao and Akshay Venkatesh.
Over all, there were around 30 talks(!) in a single week. Though it was a bit tight schedule, all talks were really nice and inspiring. Lastly, it was my great honor to attend these great conferences.

KUIAS-Heidelberg-iTHEMS joint WS "Mathematical Sciences and Medicine" was held at SUURI-COOL Kyoto on Oct. 10, 2019 with Motomu Tanaka (Heidelberg/KUIAS) and Tetsuo Hatsuda (iTHEMS) as organizers. The main aim of this workshop was to exchange ideas to create new paradigm in clinical medicine with the help of physicists, mathematicians and biologists. After the welcome address by Shigefumi Mori (Director General of KUIAS, Kyoto Univ. and Science Advisor of iTHEMS), there were 10 talks by the physicists, mathematicians and biologists from Heidelberg Univ., Kyoto Univ., Doshisha Univ. and RIKEN. Each talk was very stimulating and created lively discussions under relaxed atmosphere of SUURI-COOL Kyoto Office. To continue the discussions, we decided to have another meeting in the near future with active participation of medical doctors in Kyoto and Heidelberg.

The 2nd DMWG seminar was held on Oct.21, inviting Dr. Sekiguchi from The Univ. of Tokyo/KEK. Focusing on the weakly interacting massive particle (WIMP) case, he lectured the formation of the minimum mass DM halo in the early Universe and its implications.

WIMP is one of the strongest candidates for DM. From a theoretical point of view, neutral wino in the split-SUSY scenario is an example. One important feature of WIMP is that it achieves the current DM density, usually referred to as the relic abundance, via the so-called freeze-out mechanism. In the early Universe, the thermal equilibrium between WIMPs and the standard model (SM) particles is maintained. As the Universe expands, the temperature decreases then the WIMP annihilation rate to the SM particles becomes smaller than the expansion rate of the Universe. At this point, the number density of DM is fixed. This is the thermal freeze-out mechanism to determine the DM relic density. However, the WIMP and the SM particle are still kinetically coupled even after the thermal freeze-out. In this stage, they transfer momentum by each other through the direct scattering. By carefully calculate the epoch of the kinetic decoupling, the minimum halo mass, which is important in characterizing the DM halo properties and the observable signatures, are determined. He showed that the minimum halo mass should be of the order of O(1e-7) solar mass when we consider the neutral wino in the split SUSY scenario. This value is smaller than that expected when we neglect the kinetic decoupling effect. Furthermore, the total number of small-scale halos resides in the larger halo increases. The enhancement in the number of small-scale halos leads to a higher flux for gamma-ray annihilations in present-day halos. We have an increased possibility of detecting DM signatures in the on-going and planned astrophysical observations.