October 31, 2023 to March 31, 2024
Faculty of Science, University of Toyama
Asia/Tokyo timezone
Faculty of Science, University of Toyama
3190 Gofuku, Toyama 930-8555, Japan
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Welcome to the 5th Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2023-2024)

The Research Unit for Physics at the Cosmic Frontier, the University of Toyama will host the 5th Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2023-2024).

 This year, we provide a special lecture series about selected topics of physics in the Universe. The symposium is to discuss recent theoretical and experimental progress in physics exploring the cosmic frontier, and accelerating interdisciplinary research activities.

Information about the previous series of this symposium is available here:

Date: Oct. 31, 2023, 16:30-18:00
Room: C203

Seminar 1: Prof. Tomo Takahashi (Saga University)

"21cm line as a probe of BSM"

The redshifted 21cm line of neutral hydrogen would be a very useful probe of scenarios beyond the standard model (BSM). First I briefly review the physics of the 21cm line of neutral hydrogen, particularly focusing on the signal from the so-called dark ages. Then I will discuss some examples of how the 21cm signal can be used to probe BSM: the nature of dark matter beyond the standard CDM, dark components of the Universe such as early dark energy, and so on. Future prospects for the 21cm line observations and its implications for BSM will also be briefly discussed. 

Date: Nov. 16, 2023, 16:30-18:00
Room: A238

Seminar 2: Prof. Joe Sato (Yokohama National University)

"Lepton Flavor and Neutrino Oscillation"

Lepton flavor is an exact symmetry in the standard model. Though it is exact, it is global and accidental. Indeed it is easy to be broken by extending the SM. Therefore the search for its violation has been made since the discovery of the second flavor, muon. In this lecture we first derive the lepton flavor in the SM and see how accidental it is and how easily it is broken. It's violation is indeed seen in the neutrino oscillation phenomena. Experimentally to see its violation what we should observe and along this direction we see the reason why the neutrino oscillation is indeed interpreted as its violation. Finally we discuss how we should extend the SM to include lepton flavor violation.

Date: Dec. 12, 2023, 16:30-18:00
Room: A337

Seminar 3: Prof. Kazumi Kashiyama (Tohoku University)

"The birth of binary compact objects"

Ground-based gravitational wave interferometers like advanced LIGO, advanced VIRGO, and KAGRA have increasingly detected gravitational waves originating from the merging of binary compact objects, comprising black holes and neutron stars. How, when, and where these binary compact objects form are of immense astrophysical interest. In this presentation, I will focus on the peculiar explosive phenomena associated with the birth of binary compact objects, elaborating on their recently unveiled properties, and exploring future prospects in multi-messenger time-domain astronomy related to this subject.

Date: Jan. 16, 2024, 16:30-18:00
Room: C203

Seminar 4: Prof. Natsumi Nagata (The University of Tokyo)

"WIMP DM Heating in Neutron Stars"

Weakly Interacting Massive Particles (WIMPs) in the Universe accumulate in neutron stars (NSs) through their interactions with ordinary matter, and their annihilation inside the NS core causes late-time heating. It has been argued that this heating effect maintains the surface temperature of old NSs to be a few thousand K, which can be regarded as a smoking gun signature of dark matter (DM) heating in NSs. In this talk, I will review this DM heating mechanism and discuss its feasibility, as well as its implications for testing WIMP DM models. 

Organizing Committee

Research Unit for Physics at the Cosmic Frontier, University of Toyama

  • Masaya Hasegawa
  • Nagisa Hiroshima
  • Shigeki Hirobayashi
  • Mitsuru Kakizaki (Chair)
  • Kaori Kobayashi
  • Takeshi Kurimoto
  • Yoshiki Moriwaki
  • Yasuhiro Nariyuki
  • Eun-Kyung Park
  • Kazuhiro Yamamoto
Registration for this event is currently open.