KAGRA status

• Matteo Leonardi (NAOJ)

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.

Model experiment of cosmic ray acceleration

• Yasuhiro Kuramitsu (Osaka University)

Room: A238

Turbulent dynamos

• Nobumitsu Yokoi (University of Tokyo)

Room: A238 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.

Spontaneous structure formation of aurora due to magnetosphere-ionosphere coupling

• Seiya Nishimura (Hosei University)

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.

Non-equilibrium dynamics in warm dense matter by Free Electron Laser radiation

• Keisuke Hatada (University of Toyama)

Room: A238

Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA

• Ryosuke Sugimoto (University of Toyama)

Room: A238 Development of Auxiliary Locking System in Gravitational Wave Telescope KAGRA I'll modify it later.

Current status of intensity stabilitzation system in KAGRA

• Kanta Yamashita (University of Toyama)

Room: A238 I will fix it later.

General-relativistic magnetohydrodynamics

• Akira Mizuta (RIKEN)

Room: A238

Chiral magnetohydrodynamics in cosmology

• Tomohiro Fujita (Kyoto University)

Room: A238

Beyond the Standard Model of particle physics

• Mayumi Aoki (Kanazawa University)

Room: A238

Collider physics

• Kentarou Mawatari (Osaka U.)

Room: A238

Gravitational wave turbulence in the early Universe

• Sébastien Galtier (France)

Room: A238 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)

Laser produced-plasmas

• Shuta Tanaka (Aoyama Gakuin Universuty)

Room: A238

Dark matter interpretation of CALET data

• Holger Martin Motz (Waseda University)

Room: A238

Introduction to Neutrino Physics

• Hiroaki Sugiyama

Room: A238 I introduce basics on neutrino physics

Modeling evolution of dark matter substructure and annihilation boost

• Nagisa Hiroshima

Room: A238 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.

MeV-scale reheating temperature and cosmological constraints on sterile neutrinos

• Takuya Hasegawa (KEK)

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 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.

Testing Gauge-Higgs Unification Models by Measuring the Triple Higgs Boson Coupling at Future Collider Experiments

• Shin Suzuki (University of Toyama)

Room: A238 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.

Robustness of particle creation in a formation of a compact object

• Okabayashi Kazumasa (Osaka City University)

Room: A238 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.

Theoretical study of Photoelectron Angular Distributions for Dicationic Carbon Monoxide by the use of Full-Potential Multiple Scattering Theory

• Fukiko Ohta (University of Toyama)

Room: A238

Challenges for MCMS (Multi-Channel Multiple Scattering) theory in solid state

• Aika Takatsu

Room: A238

Machine learning for computational astrophysics

• Yosuke Matsumoto (Chiba University)

Room: A238 We present our recent progress on implementing neural network's inference into magnetohydrodynamic simulations for astrophysical phenomena.

Low-scale flavon model with a Z_N symmetry

• Tetsutaro Higaki (Keio University)

Room: A238 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.

The Higgs sector and gravitational waves

• Mitsuru Kakizaki (University of Toyama)

Room: A238 I will talk about the Higgs sector and gravitational waves.