The 2nd Toyama International Symposium on "Physics at the Cosmic Frontier" (PCF2020)
from
Tuesday, 3 March 2020 (09:00)
to
Friday, 6 March 2020 (18:00)
Monday, 2 March 2020
Tuesday, 3 March 2020
10:00
10:00  10:30
Room: A238
10:30
10:30  10:50
Room: A238
10:50
KAGRA status

Matteo Leonardi
(
NAOJ
)
KAGRA status
Matteo Leonardi
(
NAOJ
)
10:50  11:30
Room: A238
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.
11:30
Model experiment of cosmic ray acceleration

Yasuhiro Kuramitsu
(
Osaka University
)
Model experiment of cosmic ray acceleration
Yasuhiro Kuramitsu
(
Osaka University
)
11:30  12:10
Room: A238
12:10
Lunch
Lunch
12:10  13:30
Room: Cafeteria
13:30
Turbulent dynamos

Nobumitsu Yokoi
(
University of Tokyo
)
Turbulent dynamos
Nobumitsu Yokoi
(
University of Tokyo
)
13:30  14:10
Room: A238
In the presence of symmetry breakage, turbulence may contribute to suppression of effective transport, counterbalancing its primary effect: enhancement of transport. This dynamic balance leads to a largescale 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 selfconsistent 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.
14:10
Spontaneous structure formation of aurora due to magnetosphereionosphere coupling

Seiya Nishimura
(
Hosei University
)
Spontaneous structure formation of aurora due to magnetosphereionosphere coupling
Seiya Nishimura
(
Hosei University
)
14:10  14:50
Room: A238
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.
14:50
Break
Break
14:50  15:20
Room: A238
15:20
TBA

Keisuke Hatada
(
University of Toyama
)
TBA
Keisuke Hatada
(
University of Toyama
)
15:20  16:00
Room: A238
16:00
Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA

Ryosuke Sugimoto
(
University of Toyama
)
Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA
Ryosuke Sugimoto
(
University of Toyama
)
16:00  16:20
Room: A238
Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA I'll modify it later.
16:20
Current status of intensity stabilitzation system in KAGRA

Kanta Yamashita
(
University of Toyama
)
Current status of intensity stabilitzation system in KAGRA
Kanta Yamashita
(
University of Toyama
)
16:20  16:40
Room: A238
I will fix it later.
16:40
Break
Break
16:40  17:10
Room: A238
17:10
17:10  17:50
Room: GW Research Lab
Wednesday, 4 March 2020
09:00
Generalrelativistic magnetohydrodynamics

Akira Mizuta
(
RIKEN
)
Generalrelativistic magnetohydrodynamics
Akira Mizuta
(
RIKEN
)
09:00  09:40
Room: A238
09:40
Chiral magnetohydrodynamics in cosmology

Tomohiro Fujita
(
Kyoto University
)
Chiral magnetohydrodynamics in cosmology
Tomohiro Fujita
(
Kyoto University
)
09:40  10:20
Room: A238
10:20
Photo + Break
Photo + Break
10:20  10:50
Room: A238
10:50
Beyond the Standard Model of particle physics

Mayumi Aoki
(
Kanazawa University
)
Beyond the Standard Model of particle physics
Mayumi Aoki
(
Kanazawa University
)
10:50  11:30
Room: A238
11:30
Collider physics

Kentarou Mawatari
(
Osaka U.
)
Collider physics
Kentarou Mawatari
(
Osaka U.
)
11:30  12:10
Room: A238
12:10
Lunch
Lunch
12:10  13:30
Room: Cafeteria
13:30
13:30  17:30
Room: A238
Thursday, 5 March 2020
09:00
Gravitational wave turbulence in the early Universe

Sébastien Galtier
(
France
)
Gravitational wave turbulence in the early Universe
Sébastien Galtier
(
France
)
09:00  09:40
Room: A238
The nonlinear nature of the general relativity equations suggests that spacetime 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 spacetime 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 nonstationary regime the wave action spectrum presents an anomalous scaling which is understood as a selfsimilar 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)
09:40
Laser producedplasmas

Shuta Tanaka
(
Aoyama Gakuin Universuty
)
Laser producedplasmas
Shuta Tanaka
(
Aoyama Gakuin Universuty
)
09:40  10:20
Room: A238
10:20
Break
Break
10:20  10:50
Room: A238
10:50
Dark matter interpretaton of CALET data

Holger Martin Motz
(
Waseda University
)
Dark matter interpretaton of CALET data
Holger Martin Motz
(
Waseda University
)
10:50  11:30
Room: A238
11:30
Introduction to Neutrino Physics

Hiroaki Sugiyama
Introduction to Neutrino Physics
Hiroaki Sugiyama
11:30  12:10
Room: A238
I introduce basics on neutrino physics
12:10
Lunch
Lunch
12:10  13:40
Room: A238
13:40
Modeling evolution of dark matter substructure and annihilation boost

Nagisa Hiroshima
Modeling evolution of dark matter substructure and annihilation boost
Nagisa Hiroshima
13:40  14:20
Room: A238
The structure of dark matter halo is hierarchical. Among them, smallscale structures in dark matter halo, (socalled 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 gammaray observations. In order to derive the subhalo boost factors, calculations of halo structure covering more than 20 ordersofmagnitude in the halo mass up to a redshift of ~10 are required. This is beyond the capability of the current stateofart cosmological Nbody simulation which is a widelyadopted 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 crosssection obtained by isotropic gammaray observations can be updated by several factors by taking the contribution from subhalos into account.
14:20
MeVscale reheating temperature and cosmological constraints on sterile neutrinos

Takuya Hasegawa
(
KEK
)
MeVscale reheating temperature and cosmological constraints on sterile neutrinos
Takuya Hasegawa
(
KEK
)
14:20  14:40
Room: A238
In this study, we investigate a possible existence of sterile neutrinos with a various range of masses in terms of cosmology assuming an MeVscale reheating temperature. By numerically calculating sterile neutrino production through flavor mixing, we find that the existence of light sterile neutrinos inferred from shortbaseline neutrino oscillation experiments becomes consistent with observational results of bigbang 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.
14:40
Testing GaugeHiggs Unification Models by Measuring the Triple Higgs Boson Coupling at Future Collider Experiments

Shin Suzuki
(
University of Toyama
)
Testing GaugeHiggs Unification Models by Measuring the Triple Higgs Boson Coupling at Future Collider Experiments
Shin Suzuki
(
University of Toyama
)
14:40  15:00
Room: A238
GaugeHiggs Unification is a TeVscale paradigm solving the hierarchy problem. It has a characteristic Higgs potential induced by quantum corrections. In this work, as a realistic gaugeHiggs unification model we consider a SU(3) model with 5dimensional 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 HLLHC and ILC.
15:00
Break
Break
15:00  15:30
Room: A238
15:30
Universality of particle creation with a formation of a compact object

Okabayashi Kazumasa
(
Osaka City University
)
Universality of particle creation with a formation of a compact object
Okabayashi Kazumasa
(
Osaka City University
)
15:30  15:50
Room: A238
By using the fact that particle creation occur in formations of compact horizonless objects, at tempts to distinguish between a black hole and an ultra compact object are made in spherically symmetric shell models. These analyses reveal that radiation from compact objects has two burst: postHawking burst and latetime burst. However, these models are using hollow shell and not real istic for compact objects. Based on the above situation, we study particle creation in more general shell model, and find that behavior of the radiation power from a compact object have a kind of universality. This universality means that the radiation power of particle creation with a formation of compact objects does not depend on the detail of inside matter under an assumption.
15:50
TBA

Fukiko Ohta
(
University of Toyama
)
TBA
Fukiko Ohta
(
University of Toyama
)
15:50  16:10
Room: A238
16:10
TBA

Aika Takatsu
TBA
Aika Takatsu
16:10  16:30
Room: A238
Friday, 6 March 2020
09:00
Machine learning for computational astrophysics

Yosuke Matsumoto
(
Chiba University
)
Machine learning for computational astrophysics
Yosuke Matsumoto
(
Chiba University
)
09:00  09:40
Room: A238
We present our recent progress on implementing neural network's inference into magnetohydrodynamic simulations for astrophysical phenomena.
09:40
Lowscale flavon model with a Z_N symmetry

Tetsutaro Higaki
(
Keio University
)
Lowscale flavon model with a Z_N symmetry
Tetsutaro Higaki
(
Keio University
)
09:40  10:20
Room: A238
We propose a model that explains the fermion mass hierarchy by the FroggattNielsen 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 µterm 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 Higgsﬂavon sector is determined in order to make the model anomalyfree and realize a stable electroweak vacuum. We show that this model can explain the fermion mass hierarchy, realistic Higgsﬂavon 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.
10:20
Break
Break
10:20  10:50
Room: A238
10:50
The Higgs sector and gravitational waves

Mitsuru Kakizaki
(
University of Toyama
)
The Higgs sector and gravitational waves
Mitsuru Kakizaki
(
University of Toyama
)
10:50  11:30
Room: A238
I will talk about the Higgs sector and gravitational waves.
11:30
11:30  12:00
Room: A238