The 2nd Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2020)

3 Mar 2020, 09:00 → 6 Mar 2020, 18:00 Asia/Tokyo

A238 (Faculty of Science, University of Toyama)

Mitsuru Kakizaki (University of Toyama)

Welcome to the 2nd Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2020)

The Research Unit for Physics at the Cosmic Frontier, the University of Toyama will host the 2nd Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2020) from 3-6 March, 2020. The goal of the symposium is to discuss recent theoretical and experimental progress in physics exploring the cosmic frontier, and to accelerate interdisciplinary research activities.

News

• The symposium has been canceled (27 Feb.)
• The timetable has been uploaded (25 Feb.)
• The poster session has been canceled; The time slot is allocated for talks (21 Feb.)
• The symposium dinner of 5 March has been canceled (19 Feb.)

Date

Tue. morning, 3 March - Fri. noon, 6 March, 2020

Place

Gofuku Campus, University of Toyama

• Oral: Room A238 on the second floor of the Faculty of Science building
• Poster (Thu. afternoon, 5 March): Hall of the Student Union building

Deadline for Abstract Submission/Registration

18 February, 2020

Topics

• Particle Physics
• Cosmology
• Astrophysics
• General Relativity
• Plasma Physics

Invited Speakers

• Mayumi Aoki (Kanazawa University): Beyond the Standard Model of particle physics
• Tomohiro Fujita (Kyoto University): Chiral magnetohydrodynamics in cosmology
• Sebastien Galtier (LPP, Palaiseau & Inst. U. de France): Gravitational wave turbulence
• Yasuhiro Kuramitsu (Osaka University): Model experiment of cosmic ray acceleration
• Matteo Leonardi (NAOJ): KAGRA status
• Yosuke Matsumoto (Chiba University): Machine learning for computational astrophysics
• Kentarou Mawatari (Iwate University): Collider physics
• Akira Mizuta (RIKEN): General-relativistic magnetohydrodynamics
• Holger Motz (Waseda University): Dark matter interpretaton of CALET data
• Seiya Nishimura (Hosei University): Magnetosphere plasma
• Hiroaki Sugiyama (Toyama Prefectural University): Neutrinos
• Shuta Tanaka (Aoyama Gakuin University): Laser produced-plasmas
• Nobumitsu Yokoi (IIS, University of Tokyo): Turbulent dynamos
• and more

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
• Kazuhiro Yamamoto

Contact

• Mitsuru Kakizaki (University of Toyama) 
• Phone: +81-(0)76-445-6593 / email: kakizaki_at_sci.u-toyama.ac.jp

Tuesday 3 March

10:00 → 10:30 Registration

10:30 → 10:50 Opening

10:50 → 11:30 KAGRA status

After the first detection of gravitational waves coming from a binary blackhole merger in 2015, the field of gravitational wave astronomy has started. Nowadays, the second generation gravitational wave detectors LIGO (in the US) and Virgo (in Italy) have improved their sensitivity substantially with respect of the time of the first detection, increasing the detection volume of about one order of magnitude. Such improvement led to the current detection rate of one event per week, on average. In Japan, KAGRA, the first 2.5G detector, has been built and has started a commissioning phase which will lead to a joint observation run with LIGO and Virgo detectors. KAGRA has two unique features: it is located in an underground facility and has cryogenic mirrors. The first feature will allow for a reduction of the seismic and newtonian noises, which are currently limiting the low frequency region of LIGO and Virgo. The second one will help to reduce the impact of the thermal or brownian noise which is a huge limitation in the central and most sensitive frequency region of gravitational wave detectors.

Speaker: Prof. Matteo Leonardi (NAOJ)

11:30 → 12:10 Model experiment of cosmic ray acceleration

Speaker: Prof. Yasuhiro Kuramitsu (Osaka University)

12:10 → 13:30 Lunch

13:30 → 14:10 Turbulent dynamos

In the presence of symmetry breakage, turbulence may contribute to suppression of effective transport, counter-balancing its primary effect: enhancement of transport. This dynamic balance leads to a large-scale structure formation: turbulent dynamos. In this talk, firstly, an attempt to theoretically tackle strongly nonlinear and inhomogeneous turbulence is presented. Then, the theoretical results are used for constructing a self-consistent turbulent dynamo model beyond the conventional heuristic ad hoc modelling approaches. Finally, astrophysical applications of a dynamo model in strongly compressible magnetohydrodynamic turbulence will be discussed.

Speaker: Nobumitsu Yokoi (University of Tokyo)

n_yokoi_turb_dynamos_pcf2020_20200303-06.pdf

14:10 → 14:50 Spontaneous structure formation of aurora due to magnetosphere-ionosphere coupling

Feedback instability occurs in a coupling system of the magnetosphere and the ionosphere, and is a theoretical model explaining spontaneous development of the quiet aurora. In this study, we extend a model of the magnetosphere in the feedback instability to the gyrofluid model. This extension makes it possible to properly discuss kinetic effects, such as the finite Larmor radius effect, the Landau damping, and the mirror force, on the feedback instability in a framework of a fluid model. The derived model is applied to linear stability analysis and nonlinear simulation of the feedback instability.

Speaker: Seiya Nishimura (Hosei University)

14:50 → 15:20 Break

15:20 → 16:00 Non-equilibrium dynamics in warm dense matter by Free Electron Laser radiation

Speaker: Prof. Keisuke Hatada (University of Toyama)

Toyama2020_Hatada.pdf

16:00 → 16:20 Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA

Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA
I'll modify it later.

Speaker: Ryosuke Sugimoto (University of Toyama)

PCF2020.pdf

16:20 → 16:40 Current status of intensity stabilitzation system in KAGRA

I will fix it later.

Speaker: Mr Kanta Yamashita (University of Toyama)

Yamashita.pdf

16:40 → 17:10 Break

17:10 → 17:50 Tour of the Gravitational Wave Research Laboratory

Wednesday 4 March

09:00 → 09:40 General-relativistic magnetohydrodynamics

Speaker: Akira Mizuta (RIKEN)

mizuta_Toyama_200304.pdf

09:40 → 10:20 Chiral magnetohydrodynamics in cosmology

Speaker: Tomohiro Fujita (Kyoto University)

Chiral_MHD.pdf

10:20 → 10:50 Photo + Break

10:50 → 11:30 Beyond the Standard Model of particle physics

Speaker: Mayumi Aoki (Kanazawa University)

11:30 → 12:10 Collider physics

Speaker: Dr Kentarou Mawatari (Osaka U.)

12:10 → 13:30 Lunch

13:30 → 17:30 Discussion on the Universe

Thursday 5 March

09:00 → 09:40 Gravitational wave turbulence in the early Universe

The non-linear nature of the general relativity equations suggests that space-time can be turbulent. Such a turbulence may happen in the primordial universe (first second). The analytical theory of weak gravitational wave (GW) turbulence [1] was built from a diagonal space-time metric reduced to the variables t, x and y [2]. The theory predicts the existence of a dual cascade driven by 4–wave interactions with a direct cascade of energy and an inverse cascade of wave action. In the latter case the wave action spectrum - an exact solution of the equations - has the power law index -2/3 involving an explosive phenomenon. In this context, we developed a nonlinear diffusion model in spectral space to describe GW turbulence in the approximation of strongly local interactions [3]. We showed analytically that the model equation satisfies the conservation of energy and wave action, and reproduces the power law solutions previously derived from the kinetic equations. We showed numerically that in the non-stationary regime the wave action spectrum presents an anomalous scaling which is understood as a self-similar solution of the second kind.

The regime of weak GW turbulence is actually limited to a narrow wavenumber window and turbulence is expected to become strong at larger scales. Then the phenomenology of critical balance can be used. The formation of a condensate may happen and its rapid growth can be interpreted as an accelerated expansion of the universe that could be at the origin of the cosmic inflation. We can show with this scenario that the fossil spectrum obtained after inflation is compatible with the latest data obtained with the Planck/ESA satellite [4].

[1] Galtier & Nazarenko, Phys. Rev. Lett. 119, 221101 (2017)
[2] Hadad & Zakharov, J. Geom. Phys. 80, 37 (2014)
[3] Galtier, Nazarenko, Buchlin & Thalabard, Physica D 390, 84 (2019)
[4] Galtier, Nazarenko & Laurie (2020)

Speaker: Prof. Sébastien Galtier (France)

09:40 → 10:20 Laser produced-plasmas

Speaker: Prof. Shuta Tanaka (Aoyama Gakuin Universuty)

10:20 → 10:50 Break

10:50 → 11:30 Dark matter interpretation of CALET data

Speaker: Holger Martin Motz (Waseda University)

virtual_symposium_toyama_Motz.pdf

11:30 → 12:10 Introduction to Neutrino Physics

I introduce basics on neutrino physics

Speaker: Hiroaki Sugiyama

sugiyama_200305.pdf

12:10 → 13:40 Lunch

13:40 → 14:20 Modeling evolution of dark matter substructure and annihilation boost

The structure of dark matter halo is hierarchical. Among them, small-scale structures in dark matter halo, (so-called subhalos,) can enhance dark matter annihilation signals. It is necessary to quantify boost factors by those subhalos to derive the property of dark matter with current/future gamma-ray observations. In order to derive the subhalo boost factors, calculations of halo structure covering more than 20 orders-of-magnitude in the halo mass up to a redshift of ~10 are required. This is beyond the capability of the current state-of-art cosmological N-body simulation which is a widely-adopted method to study the halo structure. In this talk, I introduce our analytical approach for the formalism of subhalo evolutions and the resultant boost factors. I show that the constraints on the annihilation cross-section obtained by isotropic gamma-ray observations can be updated by several factors by taking the contribution from subhalos into account.

Speaker: Nagisa Hiroshima

14:20 → 14:40 MeV-scale reheating temperature and cosmological constraints on sterile neutrinos

In this study, we investigate a possible existence of sterile neutrinos with a various range of masses in terms of cosmology assuming an MeV-scale reheating temperature. By numerically calculating sterile neutrino production through flavor mixing, we find that the existence of light sterile neutrinos inferred from short-baseline neutrino oscillation experiments becomes consistent with observational results of big-bang nucleosynthesis (BBN) for the reheating temperature of O(1) MeV if the scalar particle responsible for the reheating fully decay into radiations. In contrast, if the scalar particle mainly decays into hadrons, the BBN bound becomes more stringent, and the allowed region for the light sterile neutrino is completely excluded, depending on the mass of the scalar particle and the hadronic branching ratio of the decay.

Speaker: Takuya Hasegawa (KEK)

14:40 → 15:00 Testing Gauge-Higgs Unification Models by Measuring the Triple Higgs Boson Coupling at Future Collider Experiments

Gauge-Higgs Unification is a TeV-scale paradigm solving the hierarchy problem. It has a characteristic Higgs potential induced by quantum corrections.
In this work, as a realistic gauge-Higgs unification model we consider a SU(3) model with 5-dimensional Lorentz symmetry relaxed. And we consider the testability of this model by measuring the triple Higgs boson coupling at future collider experiments, such as the HL-LHC and ILC.

Speaker: Shin Suzuki (University of Toyama)

PCF2020_suzuki.pdf

15:00 → 15:30 Break

15:30 → 15:50 Robustness of particle creation in a formation of a compact object

The fact that particle creation arises even in a formation of compact horizonless object has been applied to distinguish between a black hole and a black hole mimic. In this approach, it is revealed that radiation from a compact object is mainly classified into three types: transient Hawking radiation, post-Hawking burst, and late-time burst. However, these models are using a hollow shell and not realistic. Thus, we evaluate particle creation in a concrete model having matter at first.
Interestingly, similar results to the case for the hollow shell model is obtained. This implies that particle creation in a formation of a compact object has robust property. Hence, we explore how common property this robustness is in a more general shell model. In order to explore this robustness, we assume conditions between the outside and inside null coordinates of the shell and show that particle creation in a formation of a compact object is robustness in the sense that radiation power does not depend on the inside detail.

Speaker: Mr Okabayashi Kazumasa (Osaka City University)

PCF2020_Okabayashi.pdf

15:50 → 16:10 Theoretical study of Photoelectron Angular Distributions for Dicationic Carbon Monoxide by the use of Full-Potential Multiple Scattering Theory

Speaker: Fukiko Ohta (University of Toyama)

FOTA.pdf

16:10 → 16:30 Challenges for MCMS (Multi-Channel Multiple Scattering) theory in solid state

Speaker: Aika Takatsu

Takatsu.pdf

Friday 6 March

09:00 → 09:40 Machine learning for computational astrophysics

We present our recent progress on implementing neural network's inference into magnetohydrodynamic simulations for astrophysical phenomena.

Speaker: Dr Yosuke Matsumoto (Chiba University)

09:40 → 10:20 Low-scale flavon model with a Z_N symmetry

We propose a model that explains the fermion mass hierarchy by the Froggatt-Nielsen mechanism with a discrete Z_N flavor symmetry. As a concrete model, we study a supersymmetric model with a single flavon coupled to the minimal supersymmetric Standard Model. Flavon develops a TeV scale vacuum expectation value for realizing flavor hierarchy, an appropriate µ-term and the electroweak scale, hence the model has a low cutoff scale. We demonstrate how the flavon is successfully stabilized together with the Higgs bosons in the model. The discrete flavor symmetry Z_N controls not only the Standard Model fermion masses, but also the Higgs potential and a mass of the Higgsino which is a good candidate for dark matter. The hierarchy in the Higgs-flavon sector is determined in order to make the model anomaly-free and realize a stable electroweak vacuum. We show that this model can explain the fermion mass hierarchy, realistic Higgs-flavon potential and thermally produced dark matter at the same time. We discuss flavor violating processes induced by the light flavon which would be detected in future experiments.

Speaker: Tetsutaro Higaki (Keio University)

Toyama2020_Higaki.pdf

10:20 → 10:50 Break

10:50 → 11:30 The Higgs sector and gravitational waves

I will talk about the Higgs sector and gravitational waves.

Speaker: Mitsuru Kakizaki (University of Toyama)

PCF2020_Kakizaki.pdf

11:30 → 12:00 Summary, Closing