A5000675885- Black Holes and Theoretical Physics
- Cosmology and Gravitation Theories
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Noncommutative and Quantum Gravity Theories
- Astrophysics and Cosmic Phenomena
- Relativity and Gravitational Theory
- Dark Matter and Cosmic Phenomena
- Quantum Chromodynamics and Particle Interactions
- Quantum Electrodynamics and Casimir Effect
- Pulsars and Gravitational Waves Research
- Cold Atom Physics and Bose-Einstein Condensates
- Geophysics and Gravity Measurements
- Astrophysical Phenomena and Observations
- Solar and Space Plasma Dynamics
- Advanced Differential Geometry Research
- Physics of Superconductivity and Magnetism
- Quantum, superfluid, helium dynamics
- Advanced Thermodynamics and Statistical Mechanics
- High-Energy Particle Collisions Research
- Atomic and Subatomic Physics Research
- Scientific Research and Discoveries
- Quantum and electron transport phenomena
- Computational Physics and Python Applications
- Advanced Mathematical Theories and Applications
Yokohama National University
2025
Yamaguchi University
2015-2024
Tohoku University
2020-2024
National Institute of Technology, Gifu College
2015-2023
National Institute of Technology
2022
Akita Nutrition Junior College
1992-2020
Japan Women's College of Physical Education
2010-2015
University of Washington
2004-2015
The University of Tokyo
1988-2013
Yamaguchi Junior College
2009-2012
The KamLAND-Zen experiment has provided stringent constraints on the neutrinoless double-beta (0νββ) decay half-life in ^{136}Xe using a xenon-loaded liquid scintillator. We report an improved search upgraded detector with almost double amount of xenon and ultralow radioactivity container, corresponding to exposure 970 kg yr ^{136}Xe. These new data provide valuable insight into backgrounds, especially from cosmic muon spallation xenon, have required use novel background rejection...
We report on a search for electron antineutrinos ($\bar{\nu}_e$) from astrophysical sources in the neutrino energy range 8.3 to 30.8 MeV with KamLAND detector. In an exposure of 6.72 kton-year liquid scintillator, we observe 18 candidate events via inverse beta decay reaction. Although there is large background uncertainty neutral current atmospheric interactions, find no significant excess over model predictions. Assuming several supernova relic spectra, give upper flux limits 60--110...
Abstract There has been much discussion about the initial conditions of early Universe in context quantum theory. In this paper, we construct wave function and probability distribution by adopting version BPS equation instead usual Wheeler‒DeWitt a minisuperspace cosmology with spatially uniform scalar fields. Although model treated study is technically valid for limited form potential, show that it possible to conserved current our model. We also examine classical aspects models...
Neutral current single π0 production induced by neutrinos with a mean energy of 1.3 GeV is measured using 1000 ton water Cherenkov detector in the K2K long baseline neutrino experiment. The cross section for this process relative to total charged be 0.064±0.001(stat.)±0.007(sys.). momentum distribution neutral π0s from target high statistics first time.
Abstract The decay of the primordial isotopes 238 U, 235 232 Th, and 40 K has contributed to terrestrial heat budget throughout Earth's history. Hence, individual abundance those are key parameters in reconstructing contemporary Earth models. geoneutrinos produced by radioactive decays uranium thorium have been observed with Kamioka Liquid‐Scintillator Antineutrino Detector (KamLAND). Those measurements improved more than 18‐year observation time, improvement detector background levels...
We present a search for electron neutrino appearance from accelerator-produced muon neutrinos in the K2K long-baseline experiment. One candidate event is found data corresponding to an exposure of $4.8\ifmmode\times\else\texttimes\fi{}{10}^{19}$ protons on target. The expected background absence oscillations estimated be $2.4\ifmmode\pm\else\textpm\fi{}0.6$ events and dominated by misidentification neutral current ${\ensuremath{\pi}}^{0}$ production. exclude...
We measured the soft error rates (SER) of SRAM devices in several field tests, and obtained SERs induced independently by high energy neutrons, thermal neutrons alpha particles. It was found that neutron SER approximately three times larger than 0.18 /spl mu/m 8M SRAMs, particle negligible. also performed accelerated tests for using a nuclear reactor, can be reduced factors up to hundreds shield sheets or eliminating BPSG layers.
The high energy neutron-induced SSER and ASER in SRAMs were compared, a large discrepancy of factor 2.6 was observed. We investigated the possible causes this discrepancy, including accuracy neutron flux, flux effect, incident angle dependence, temperature time variation cosmic rays, etc. As result, we concluded that originates from value assumed for at sea level. normalized our results to 0.18 /spl mu/m so as not use SER 0.13 16 Mb SRAM is approximately 270 FIT/Mb.
We study covariant equations in quantum cosmology of an extended minisuperspace obtained by the Eisenhart--Duval lift. find that a Dirac-type equation is naturally introduced minisuperspace. Explicit forms fundamental solutions are yielded for specific models. The possible further development this direction also discussed.
Recently, Falomir, Gamboa, Mendez, Gondolo and Maldonado proposed a bicosmology scenario [1-4] for solving some cosmological problems related to inflation, dark matter, thermal history of the universe. Their plan is introduce noncommutativity into momentum space two scale factors. In present paper, we revisit their model first consider exact classical solutions in with constant between dynamical variables canonical momenta. We also hypothesize that appears when factors are small, show...
The quantum stress tensor near a three-dimensional black hole is studied for conformally coupled scalar field. back reaction to the metric also investigated.Received 28 September 1993DOI:https://doi.org/10.1103/PhysRevD.49.5286©1994 American Physical Society
It is shown that by taking the effect of Earth into account possible observation electron neutrinos from supernova SN1987A at Kamiokande II compatible with solution solar neutrino puzzle Mikheyev-Smirnov-Wolfenstein mechanism. Our scenario requires relatively large mixing angles sin 2 2θ ≳ 0.3 and, most probably, ∆m order 10 −6 ~ −5 (eV) . The implications in other detectors are briefly discussed.
Adopting a simple ansatz, we find exact solutions to the Einstein-Maxwell-dilaton equations, which stand for multi-black hole configuration with maximal charge in cosmological metric and dilaton field background driven by term.
A family of static multicentered solutions to modified Einstein-Maxwell equations coupled with a dilaton is constructed in $(1+N)$ dimensional space-time ($N\ge 2$). For $N\ge 3$, the are generalizations Majumdar-Papapetrou solution. We also find solution $(1+2)$ dimensions, where scalar and vector forces cancel each other case. The interaction between two extreme charged black holes low-energy limit investigated dimensions 3$). that there remains residual velocity-dependent force general...
In double field theory, the equation of motion for a point particle in background is considered. We find that described by geodesic flow doubled geometry. Inspired analysis on motion, we consider modified model quantum string cosmology, which includes two scale factors.
The authors study the quantum effect of self-interacting fields in classical background conical space, i.e. around a cosmic string with infinitesimal width. renormalized value $\langle\phi^2\rangle$ and energy-momentum tensor presence strings are calculated scalar field theory. amount condensation is also estimated case Dirac Lagrangian four-fermion interaction. physical implications above analyses discussed.
In this paper, we study rotating boson stars in the large coupling limit as well Newtonian limit. We investigate equilibrium solutions four and five dimensions by adopting some analytical approximations. show that relations among radius, angular momentum, energy, quadrupole moment (for four-dimensional solution) of star can be qualitatively realized for minimal number boson-star parameters.
Abstract Preceding a core-collapse supernova (CCSN), various processes produce an increasing amount of neutrinos all flavors characterized by mounting energies from the interior massive stars. Among them, electron antineutrinos are potentially detectable terrestrial neutrino experiments such as KamLAND and Super-Kamiokande (SK) via inverse beta decay interactions. Once these pre-supernova (pre-SN) observed, early warning upcoming CCSN can be provided. In light this, SK, both located in...
We study vortex solutions in the Born-Infeld theory coupled with a complex scalar field. show that for specific form of "Higgs" potential satisfies set Bogomol'nyi-type equations. Another model, nonlinear interaction between gauge and Higgs fields, is also considered. how it derived from supersymmetric extension minimally
We consider the third quantization in quantum cosmology of a minisuperspace extended by Eisenhart-Duval lift. study based on both Klein-Gordon type and Dirac-type equations minisuperspace. Spontaneous creation "universes" is investigated upon simple model. find that wave function reveals number density universes expressed Fermi-Dirac distribution. also calculate entanglement entropy multi-universe system.
We solve Einstein equations coupled to a complex scalar field with infinitely large self-interaction, degenerate fermions, and negative cosmological constant in $(2+1)$ dimensions. Exact solutions for static boson-fermion stars are found when circular symmetry is assumed. find that the minimum binding energy of star takes value if sufficiently small.
We calculate the Euclidean propagator for a conformally coupled massless scalar field in background of three-dimensional black hole. The expectation value Hartle--Hawking state is obtained spacetime.