# Welcome to the 3rd Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2021)

The Research Unit for Physics at the Cosmic Frontier, the University of Toyama will host the** 3rd Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2021). **

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:

- PCF 2020 https://indico.cern.ch/event/862539/
- PCF 2019 https://indico.cern.ch/event/791504/

### Date: Part 2

**Lecture 1: February 8, 2022, 14:45-16:15 (JST), Dr. Yoshihiro Kajimura (NIT, Akashi College)**

**"****Performance evaluation of magnetic plasma shield for protecting the cosmic radiation and obtaining the thrust****"**

The protection from cosmic rays is one of the serious problem in long-term space missions scheduled in the future. We propose a method to protect the spacecraft and human bodies from the cosmic rays by using the magnetic shield generated by the coil current and plasma ring current generated by injected thermal plasma from interplanetary spacecraft. Also the magnetic field for the shield can be used as the magnetic sail for obtaining the thrust from the solar wind plasma. The performance evaluation of magnetic plasma shield for protecting the cosmic radiation and obtaining the thrust will be presented in the symposium.

**Lecture 2: February 22, 2022, 14:45-16:15 (JST), Dr. Naoki Sato (The University of Tokyo)**

**"****Hamiltonian mechanics, Nambu mechanics, and generalized phase space****"**

The equations of motion governing ideal mechanical systems can be written through Hamilton’s canonical equations, which encapsulate Newton’s second law of motion. Phase space is spanned by canonically paired variables(𝑝,𝑞) representing the components of particle position and momentum. In his 1973 paper, starting from the dynamics of a rigid body, Yoichiro Nambu proposed a generalization of Hamiltonian mechanics to a three-dimensional phase space: instead of canonical pairs (𝑝,𝑞), the building block of the phase space is a canonical triplet (𝑝,𝑞,𝑟), while the number of Hamiltonians is increased to two (𝐺,𝐻). For a rigid body the canonical triplet corresponds to the components of angular momentum, while the Hamiltonians are energy and total angular momentum respectively. Unfortunately, such generalization of Hamiltonian mechanics is not straightforward due to the difficulty in replacing the Jacobi identity characterizing the Poisson algebra of Hamiltonian systems with a more general axiom. In this talk, after reviewing basic aspects of Hamiltonian mechanics, we discuss the axiomatic formulation of Nambu mechanics, and present a possible formulation of generalized Hamiltonian mechanics in 3-dimensional phase space by introducing a symplectic 3-form, a closed differential form of degree 3 replacing the usual symplectic 2-form. We show that in the proposed theory an analogous of the classical Lie-Darboux theorem holds, ensuring the existence of a Liouville measure for the generalized phase space.

**Lecture 3: March 8, 2022, 14:45-16:15 (JST), Dr. Kirolosse Girgis (Kyushu University/Cairo University****)**

**"****The South Atlantic Anomaly: Variations of its Magnetic Field, Proton Flux and Radiation Environment due to Space Weather Conditions****"**

Low-Earth Orbit (LEO) missions are subject to intense radiation doses due to their passage into the inner radiation belt, in addition to the South Atlantic Anomaly (SAA), where the lowest magnetic field intensity is located, so that the particles from the radiation belts are precipitated into the anomaly zone. Recent studies indicated that the SAA was generally affected by space weather conditions.

Therefore, we have studied the magnetic field variations of the SAA by implementing various semi-empirical geomagnetic fields according to different solar wind conditions. The proton flux response was investigated by simulating the inner radiation belt through developing several 3D relativistic test particle simulation codes for several geomagnetic conditions. Then, we estimated the corresponding radiation environment for a LEO mission during a geomagnetic storm event.

The previous numerical results showed good agreement with observations from satellites, in particular, the flux enhancement of the SAA southern cell.

**Lecture 4: March 22, 2022, 14:45-16:15 (JST), Dr. Kiwamu Izumi (JAXA****)**

**"****An overview of space gravitational wave observations****"**

We are now living in an exciting era. Since the first direct detection of gravitational waves in 2015, the ground-based gravitational wave detectors keep collecting the gravitational wave events. In the mean time, the success of the LISA Pathfinder mission in 2016 paved the way towards achieving the future gravitational wave observations from space. In this talk, I will give a brief overview of the scientific objectives and current status of the space gravitational wave observations including LISA and other concepts.

### Date: Part 1

**Lecture 1: December 7, 2021, 14:45-16:15 (JST), Dr. Masato Yamanaka (Osaka City University)**

**"Overview of Lepton Flavor Violation"**

The standard model of particle physics is far from accounting for mysteries about our universe, --e.g., what is dark matter and dark energy?-- and it must be extended to a more fundamental description of nature. Such new physics models allow Lepton Flavor Violating (LFV) reactions (e.g., muon decays into an electron and a photon) which are exactly forbidden in the standard model. Hence search for LFV is a clue to the new physics, which unveil the flavor structure and the symmetries behind it. In this talk, the general features of the LFV processes are introductory reviewed, and theoretical and experimental progresses are discussed.

**Lecture 2: December 14, 2021, 14:45-16:15 (JST), Dr. Kei Yagyu (Osaka University)**

**"New horizons in particle physics explored by Higgs physics"**

It has been nine years since the Higgs boson was discovered at LHC.

However, the essence of Higgs physics, i.e., the origin of the spontaneous breaking of electroweak symmetry, has not yet been clarified.On the other hand, a new physics model beyond the Standard Model (SM) must exist, due to phenomena which cannot be explained in the SM such as the baryon number asymmetry of the Universe. In this talk, I will first give a brief review of the Higgs physics, and then discuss the possibility that the determination of the structure of the Higgs sector is a "key" to explore new physics beyond the SM by introducing recent my works.

**Lecture 3: December 21, 2021, 14:45-16:15 (JST), Dr. Toshihiro Fujii (Kyoto University)**

**"Unraveling mysteries of the most energetic particle in the universe"**

Clarifying origins and acceleration mechanisms of the most energetic particles in the universe has been a decades-long endeavor, being one of the most intriguing mysteries in the interdisciplinary research among astroparticle physics, high-energy physics and nuclear physics. Since such ultra-high-energy cosmic rays (UHECRs) are deflected less strongly by the galactic and inter-galactic magnetic fields, due to their enormous kinetic energies, their arrival directions are ostensively correlated with their origins. A next-generation astronomy using UHECRs is hence a potentially viable probe to unravel mysteries of extremely energetic phenomena in the nearby universe. In this talk, I will highlight the introductory cosmic-ray physics, detection techniques and latest results of the two giant observatories, dubbed Telescope Array experiment and Pierre Auger Observatory including their on-going upgrades and address scientific objectives and requirements for future UHECR observatories.

### Place

Gofuku Campus, University of Toyama & zoom

- onsite: Room A238 on the second floor of the Faculty of Science building
- online: The zoom URL is shared with the registered participants

**Topics**

- lepton flavor violation (Lecture 1)
- Higgs physics (Lecture 2)
- ultra-high-energy cosmic-ray (Lecture 3)

### Organizing Committee

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

- Masaya Hasegawa
- Nagisa Hiroshima
- Shigeki Hirobayashi
- Mitsuru Kakizaki (Chair)
- Kaori Kobayashi
- Yoshiki Moriwaki
- Yasuhiro Nariyuki
- Eun-Kyung Park
- Kazuhiro Yamamoto