Results for "Katsuya Hashino"

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Gravitational waves from first order electroweak phase transition in models with the $U(1)_X^{}$ gauge symmetryFeb 08 2018We consider a standard model extension equipped with a dark sector where the $U(1)_X^{}$ Abelian gauge symmetry is spontaneously broken by the dark Higgs mechanism. In this framework, we investigate patterns of the electroweak phase transition as well ... More
Synergy between measurements of the gravitational wave and the triple Higgs coupling in probing first order phase transitionApr 07 2016Jul 20 2016Probing the Higgs potential and new physics behind the electroweak symmetry breaking is one of the most important issues of particle physics. In particular, nature of electroweak phase transition is essential for understanding physics at the early Universe, ... More
Discriminative phenomenological features of scale invariant models for electroweak symmetry breakingAug 13 2015Aug 19 2015Classical scale invariance (CSI) may be one of the solutions for the hierarchy problem. Realistic models for electroweak symmetry breaking based on CSI require extended scalar sectors without mass terms, and the electroweak symmetry is broken dynamically ... More
Gravitational waves and Higgs boson couplings for exploring first order phase transition in the model with a singlet scalar fieldSep 01 2016We calculate the spectrum of gravitational waves originated from strongly first order electroweak phase transition in the extended Higgs model with a real singlet field. In order to calculate the bubble nucleation rate, we perform a two-field analysis ... More
Study of high pressure gas filled RF cavities for muon colliderFeb 06 2015Muon collider is a considerable candidate of the next-generation high-energy lepton collider machine. Operating an RF cavity in a multi-Tesla magnet is a critical requirement in a muon accelerator and a cooling channel. However, the maximum RF gradient ... More
Damped Lyman alpha Absorbing Galaxies At Low Redshifts z<1 From Hierarchical Galaxy Formation ModelsDec 21 2004We investigate Damped Ly-alpha absorbing galaxies (DLA galaxies) at low redshifts z<1 in the hierarchical structure formation scenario to clarify the nature of DLA galaxies because observational data of such galaxies mainly at low redshifts are currently ... More
On the field intersection problem of quartic generic polynomials via formal Tschirnhausen transformationDec 28 2008Jun 24 2009Let $k$ be a field of characteristic $\neq 2$. We give an answer to the field intersection problem of quartic generic polynomials over $k$ via formal Tschirnhausen transformation and multi-resolvent polynomials.
On the field intersection problem of generic polynomials: a surveyOct 02 2008Jun 09 2009Let $k$ be a field of characteristic $\neq 2$. We survey a general method of the field intersection problem of generic polynomials via formal Tschirnhausen transformation. We announce some of our recent results of cubic, quartic and quintic cases the ... More
The non-commutative Specker phenomenon in the uncountable caseNov 27 2000An infinitary version of the notion of free products has been introduced and investigated by G.Higman. Let G_i (for i in I) be groups and ast_{i in X} G_i the free product of G_i (i in X) for X Subset I and p_{XY}: ast_{i in Y} G_{i}->ast_{i in X} G_{i} ... More
On the field intersection problem of solvable quintic generic polynomialsApr 30 2008Jun 23 2009We study a general method of the field intersection problem of generic polynomials over an arbitrary field $k$ via formal Tschirnhausen transformation. In the case of solvable quintic, we give an explicit answer to the problem by using multi-resolvent ... More
A list of all integrable 2D homogeneous polynomial potentials with a polynomial integral of order at most 4 in the momentaAug 29 2001We searched integrable 2D homogeneous polynomial potential with a polynomial first integral by using the so-called direct method of searching for first integrals. We proved that there exist no polynomial first integrals which are genuinely cubic or quartic ... More
Cotorsion-free groups from a topological viewpointSep 01 2014We present a characterization of cotorsion-free abelian groups in terms of homomorphisms from fundamental groups of Peano continua, which aligns naturally with the generalization of slenderness to non-abelian groups. In the process, we calculate the first ... More
Abelian spatial string tension in finite temperature SU(2) gauge theoryDec 06 2016We investigate Abelian and monopole contributions to spatial string tension in the deconfined phase of finite temperature SU(2) gauge theory without imposing any gauge fixing conditions. Lattice calculations of non-Abelian and Abelian spatial string tensions ... More
A note on the field isomorphism problem of X^3+sX+s and related cubic Thue equationsJan 30 2009Jul 14 2009We study the field isomorphism problem of cubic generic polynomial $X^3+sX+s$ over the field of rational numbers with the specialization of the parameter $s$ to nonzero rational integers $m$ via primitive solutions to the family of cubic Thue equations ... More
A geometric framework for the subfield problem of generic polynomials via Tschirnhausen transformationOct 01 2007Oct 15 2008Let $k$ be an arbitrary field. We study a general method to solve the subfield problem of generic polynomials for the symmetric groups over $k$ via Tschirnhausen transformation. Based on the general result in the former part, we give an explicit solution ... More
Semi-Static Hedging Based on a Generalized Reflection Principle on a Multi Dimensional Brownian MotionApr 23 2011Oct 15 2012On a multi-assets Black-Scholes economy, we introduce a class of barrier options. In this model we apply a generalized reflection principle in a context of the finite reflection group acting on a Euclidean space to give a valuation formula and the semi-static ... More
Entropy of monopoles from percolating cluster in quenched SU(2) QCDAug 05 2003The length distribution and the monopole action of the infrared monopole clusters are studied numerically in quenched SU(2) QCD. We determine the effective entropy of the monopole currents which turns out to be a descending function of the blocking scale, ... More
Numerical determination of monopole entropy in pure SU(2) QCDJun 01 2003We study numerically the length distributions of the infrared monopole clusters in pure SU(2) QCD. These distributions are Gaussian for all studied blocking steps of monopoles, lattice volumes and lattice coupling constant. We also investigate the monopole ... More
Evolution of Multiphase Hot Interstellar Medium in Elliptical GalaxiesJun 05 1997We present the results of a variety of simulations concerning the evolution of multiphase (inhomogeneous) hot interstellar medium (ISM) in elliptical galaxies. We assume the gases ejected from stars do not mix globally with the circumferential gas. The ... More
On 2-dimensional nonaspherical cell-like Peano continua: A simplified approachFeb 17 2013We construct a functor $AC(-,-)$ from the category of path connected spaces $X$ with a base point $x$ to the category of simply connected spaces. The following are the main results of the paper: (i) If $X$ is a Peano continuum then $AC(X,x)$ is a cell-like ... More
Rigidity of the Minimal Grope GroupAug 04 2006We give a systematic definition of the fundamental groups of gropes, which we call grope groups. We show that there exists a nontrivial homomorphism from the minimal grope group M to another grope group G only if G is the free product of M with another ... More
Energy-entropy study of projected space-like monopoles in finite-T quenched SU(2) QCDSep 04 2003Properties of space-like monopoles projected on the 3D space in finite temperature quenched SU(2) QCD are studied. The monopole energy is derived from the effective action of the monopoles which is determined by an inverse Monte-Carlo method. Then the ... More
Multifractal Dimensions for Branched GrowthJul 12 1996A recently proposed theory for diffusion-limited aggregation (DLA), which models this system as a random branched growth process, is reviewed. Like DLA, this process is stochastic, and ensemble averaging is needed in order to define multifractal dimensions. ... More
On the second homotopy group of $SC(Z)$Oct 03 2009In our earlier paper (K. Eda, U. Karimov, and D. Repov\v{s}, \emph{A construction of simply connected noncontractible cell-like two-dimensional Peano continua}, Fund. Math. \textbf{195} (2007), 193--203) we introduced a cone-like space $SC(Z)$. In the ... More
Prospects of the Nambu BracketApr 11 2016May 20 2016We review recent progress in formulating the worldvolume theory of M2-branes using the Nambu bracket. Although it is generally agreed that this formulation should be replaced by another using the superconformal Chern-Simons theory, we try to pursue a ... More
On the singular homology of one class of simply-connected cell-like spacesMay 14 2011Aug 05 2011In our earlier papers we constructed examples of 2-dimensional nonaspherical simply-connected cell-like Peano continua, called {\sl Snake space}. In the sequel we introduced the functor $SC(-,-)$ defined on the category of all spaces with base points ... More
Blocked lattice monopoles in quenched SU(2) QCD and dual superconductor modelAug 10 2003We study the action of the lattice monopoles in quenched SU(2) QCD in the Maximal Abelian projection. We relate the lattice action of the monopole currents to the monopole degrees of freedom of the continuum dual superconductor model and obtain the value ... More
A construction of noncontractible simply connected cell-like two dimensional Peano continuaJul 27 2007Using the topologist sine curve we present a new functorial construction of cone-like spaces, starting in the category of all path-connected topological spaces with a base point and continuous maps, and ending in the subcategory of all simply connected ... More
Determination of monopole condensate from monopole action in quenched SU(2) QCDAug 21 2003We study the effective monopole action obtained in the Maximal Abelian projection of quenched SU(2) lattice QCD. We determine the quadratic part of the lattice action using analytical blocking from continuum dual superconductor model to the lattice model. ... More
Effective Monopole Action at Finite Temperature in SU(2) GluodynamicsDec 17 2001Effective monopole action at finite temperature in SU(2) gluodynamics is studied on anisotropic lattices. Using an inverse Monte-Carlo method and the blockspin transformation for space directions, we determine 4-dimensional effective monopole action at ... More
Entropy of spatial monopole currents in pure SU(2) QCD at finite temperatureMar 19 2005We study properties of space-like monopole trajectories in the Maximal Abelian gauge of quenched SU(2) QCD at the finite temperature. We concentrate on infrared monopole clusters which are responsible for the confinement properties of the theory. We determine ... More
Monopole gas in three dimensional SU(2) gluodynamicsJul 30 2004We study properties of the Abelian monopoles in the Maximal Abelian projection of the three dimensional pure SU(2) gauge model. We match the lattice monopole dynamics with the continuum Coulomb gas model using a method of blocking from continuum. We obtain ... More
A nonaspherical cell-like 2-dimensional simply connected continuum and related constructionsMar 29 2008Feb 01 2009We prove the existence of a 2-dimensional nonaspherical simply connected cell-like Peano continuum (the space itself was constructed in one of our earlier papers). We also indicate some relations between this space and the well-known Griffiths' space ... More
Atomically Resolved Surface Structure of SrTiO3(001) Thin Films Grown in Step-Flow Mode by Pulsed Laser DepositionApr 01 2010The surface structure of SrTiO3(001) thin films homoepitaxially grown by PLD in step-flow mode was characterized using low temperature STM. It was found that one-dimensional (1D) TiOx-based nanostructures were formed on the thin film surface and their ... More
Constraining stellar properties of intervening damped Lyα and MgII absorbing galaxies toward GRB 050730Jul 24 2012We performed multi-band deep imaging of the field around GRB 050730 to identify the host galaxies of intervening absorbers, which consist of a damped Ly{\alpha} absorption (DLA) system at zabs=3.564, a sub-DLA system at zabs=3.022, and strong MgII absorption ... More
Analysis of Optimal Velocity Model with Explicit DelayMay 12 1998We analyze Optimal Velocity Model (OVM) with explicit delay. The properties of congestion and the delay time of car motion are investigated by analytical and numerical methods. It is shown that the small explicit delay time has almost no effects. In the ... More
Gauge invariant 'monopoles' and color confinement mechanismNov 15 2005The dual Meissner effect is described and numerically observed in a gauge-invariant way in lattice Monte-Carlo simulations of pure SU(2) QCD. A gauge-invariant monopole-like quantity on the lattice is defined by a gauge-invariant Abelian-like field strength. ... More
Abelian dominance in local unitary gauges and without gauge-fixing in pure SU(2) QCDMar 09 2007We perform lattice Monte-Carlo simulations of pure SU(2) QCD using the multi-level method. We find Abelian dominance in local unitary gauges such as those diagonalizing a plaquette. A static potential described by Abelian link fields alone gives us the ... More
The Dual Meissner Effect and Magnetic Displacement CurrentsOct 01 2004Mar 08 2005The dual Meissner effect is observed without monopoles in quenched $SU (2)$ QCD with Landau gauge-fixing. Magnetic displacement currents which are time-dependent Abelian magnetic fields play a role of solenoidal currents squeezing Abelian electric fields. ... More
HI-selected Galaxies as a probe of Quasar Absorption SystemsFeb 02 2010We investigate the properties of HI-rich galaxies detected in blind radio surveys within the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. By drawing a detailed comparison between the properties of HI-selected ... More
A Conformational Search Method for Protein Systems Using Genetic Crossover and Metropolis CriterionMay 21 2015Many proteins carry out their biological functions by forming the characteristic tertiary structures. Therefore, the search of the stable states of proteins by molecular simulations is important to understand their functions and stabilities. However, ... More
Radiation hydrodynamics simulations of wide-angle outflows from super-critical accretion disks around black holesDec 15 2014By performing two-dimensional radiation hydrodynamics simulations with large computational domain of 5000 Schwarzschild radius, we revealed that wide-angle outflow is launched via the radiation force from the super-critical accretion flows around black ... More
Abelian dominance and the dual Meissner effect in local unitary gauges in SU(2) gluodynamicsMar 09 2007Performing highly precise Monte-Carlo simulations of SU(2) gluodynamics, we observe for the first time Abelian dominance in the confining part of the static potential in local unitary gauges such as the F12 gauge. We also study the flux-tube profile between ... More
Gauge invariance of the Abelian dual Meissner effect in pure SU(2) QCDNov 15 2005The dual Meissner effect is described and numerically observed in a gauge-invariant way in lattice Monte-Carlo simulations in pure SU(2) QCD. The squeezing of the non-Abelian electric field between a pair of static quark and anti-quark occurs due to the ... More
The dual Meissner effect in SU(2) Landau gaugeOct 25 2004The dual Meissner effect is observed without monopoles in quenched SU(2) QCD with Landau gauge-fixing. Abelian as well as non-Abelian electric fields are squeezed. Magnetic displacement currents which are time-dependent Abelian magnetic fields play a ... More
Direct observation of the washboard noise of a driven vortex lattice in a high-temperature superconductor, Bi2Sr2CaCu2OySep 29 2000We studied the conduction noise spectrum in the vortex state of a high-temperature superconductor, Bi2Sr2CaCu2Oy, subject to a uniform driving force. Two characteristic features, a broadband noise (BBN) and a narrow-band noise (NBN), were observed in ... More
On Snake cones, Alternating cones and related constructionsMay 27 2013We show that the Snake on a square $SC(S^1)$ is homotopy equivalent to the space $AC(S^1)$ which was investigated in the previous work by Eda, Karimov and Repov\vs. We also introduce related constructions $CSC(-)$ and $CAC(-)$ and investigate homotopical ... More
Delay of Vehicle Motion in Traffic DynamicsAug 06 1996We demonstrate that in Optimal Velocity Model (OVM) delay times of vehicles coming from the dynamical equation of motion of OVM almost explain the order of delay times observed in actual traffic flows without introducing explicit delay times. Delay times ... More
Recent Progress of RF Cavity Study at Mucool Test AreaJan 27 2012In order to develop an RF cavity that is applicable for a muon beam cooling channel, a new facility, called Mucool Test Area (MTA) has been built at Fermilab. MTA is a unique facility whose purpose is to test RF cavities in various conditions. There are ... More
Stripe charge ordering in SrO-terminated SrTiO3(001) surfacesFeb 01 2011The local electronic structure of the SrO-terminated SrTiO3(001) surface was explored using scanning tunneling microscopy. At low bias voltages in the empty states, a unidirectional structure with a periodicity of 3 unit cells, superimposed on a c(2 x ... More
Thickness-dependent Local Surface Electronic Structures of Homoepitaxial SrTiO3 Thin FilmsApr 16 2010We have investigated the atomically-resolved substrate and homoepitaxial thin film surfaces of SrTiO3(001) using low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) combined with pulsed laser deposition (PLD). It was found that annealing ... More
Combination of genetic crossover and replica-exchange method for conformational search of protein systemsMay 21 2015We combined the genetic crossover, which is one of the operations of genetic algorithm, and replica-exchange method in parallel molecular dynamics simulations. The genetic crossover and replica-exchange method can search the global conformational space ... More
Gauge invariance of the dual Meissner effect in QCDNov 15 2005The dual Meissner effect is described and numerically observed in a gauge-invariant way in lattice Monte-Carlo simulations of pure SU(2) QCD. A gauge-invariant Abelian-like field strength is defined in terms of a unit-vector in color space which is constructed ... More
Gauge-independent Abelian mechanism of color confinement in gluodynamicsJun 29 2007Abelian mechanism of non-Abelian color confinement is observed in a gauge-independent way by high precision lattice Monte Carlo simulations in gluodynamics. An Abelian gauge field is extracted with no gauge-fixing. A static quark-antiquark potential derived ... More
Chemical Enrichment in Damped Lyman Alpha Systems From Hierarchical Galaxy Formation ModelsNov 25 2003We investigate chemical enrichment in Damped Lyman alpha (DLA) systems in the hierarchical structure formation scenario using a semi-analytic model of galaxy formation. The model developed by Nagashima, Totani, Gouda and Yoshii takes into account various ... More
New anti-perovskite-type Superconductor ZnNyNi3Nov 21 2008We have synthesized a new superconductor ZnNyNi3 with Tc ~3 K. The crystal structure has the same anti-perovskite-type such as MgCNi3 and CdCNi3. As far as we know, this is the third superconducting material in Ni-based anti-perovskite series. For this ... More
Atomic-scale visualization of initial growth of homoepitaxial SrTiO3 thin film on an atomically ordered substrateOct 25 2011The initial homoepitaxial growth of SrTiO3 on a (\surd13\times\surd13) - R33.7{\deg}SrTiO3(001) substrate surface, which can be prepared under oxide growth conditions, is atomically resolved by scanning tunneling microscopy. The identical (\surd13\times\surd13) ... More
Measurement and control of spatial qubits generated by passing photons through double-slitsMay 08 2008We present an experimental study of the non-classical correlations of a pair of spatial qubits formed by passing two down-converted photons through a pair of double slits. After confirming the entanglement generated in our setup by quantum tomography ... More
Magnetic Field versus Temperature Phase Diagram of the Spin-1/2 Alternating Chain Compound F5PNNNov 15 2007We have measured the specific heat of the S = 1/2 alternating Heisenberg antiferromagnetic chain compound pentafluorophenyl nitronyl nitroxide in magnetic fields using a single crystal and powder. A sharp peak due to field-induced magnetic ordering (FIMO) ... More
Extended Lyman-alpha emission from a high-z DLA at z=3.115Nov 21 2013Nov 22 2013We searched for star formation activity associated with high-z Damped Lyman-alpha systems (DLAs) with Subaru telescope. We used a set of narrow-band (NB) filters whose central wavelengths correspond to the redshifted Lyman-alpha emission lines of targeted ... More
Type-Ia Supernova Remnant Shell At $Z=3.5$ Seen In The Three Sightlines Toward The Gravitationally Lensed Qso B1422+231Jun 16 2012Using the Subaru 8.2m Telescope with an IRCS Echelle spectrograph, we obtained high-resolution (R=10,000) near-infrared (1.01-1.38 \mu m) spectra of images A and B of the gravitationally lensed QSO B1422+231 (z=3.628) consisting of four known lensed images. ... More
Pressure induced magnetic ordering in Yb2Pd2Sn with two quantum critical pointsApr 25 2007May 30 2007Pressure induced long range antiferromagnetic order is discovered in Yb2Pd2Sn by measuring the electrical resistivity under pressure up to 5.0 GPa. Magnetic ordering is observed above about 1.0 GPa, being the lowest pressure in Yb-intermetallics showing ... More
Incommensurate--commensurate transitions in the mono-axial chiral helimagnet driven by the magnetic fieldMar 02 2016The zero temperature phase diagram of the mono-axial chiral helimagnet in the magnetic field plane formed by the components parallel and perpendicular to the helical axis is thoroughly analyzed. The nature of the transition to the commensurate state depends ... More
Topological defects and equation of state of gluon plasmaOct 15 2007We show that the degrees of freedom associated with magnetic monopole- and vortexlike gluonic configurations make a strong contribution to the anomaly of the energy-momentum tensor of Yang-Mills theory in the deconfinement phase immediately above the ... More
Superconductivity in Room Temperature Stable electride and high-pressure phases of alkali metalsJan 24 2015S-band metals such as alkali and alkaline earth metals do not undergo a superconducting transition (SCT) at an ambient pressure, but their high-pressure phases do. In contrast, room temperature stable electride electride (C12A7:e-) in which anionic electrons ... More
Charge ordering in the intermediate valence magnet YbPdMar 20 2013An x-ray diffraction study reveals the charge ordering structure in an intermediate valence magnet YbPd with a CsCl-structure. The valence of the Yb ions forms an incommensurate structure, characterized by the wavevector (+-0.07 +-0.07 1/2) below 130 ... More
Experimental and theoretical evidence for pressure-induced metallization in FeO with the rock-salt type structureDec 21 2011Electrical conductivity of FeO was measured up to 141 GPa and 2480 K in a laserheated diamond-anvil cell. The results show that rock-salt (B1) type structured FeO metallizes at around 70 GPa and 1900 K without any structural phase transition. We computed ... More
Interplay between Charge and Magnetic Ordering in YbPdJun 11 2013The pressure-temperature phase diagram of an intermediate-valence compound YbPd was revealed via simultaneous ac-calorimetry and electrical resistivity measurements. Two successive structural phase transition temperatures, $T_1$ = 125 K and $T_2$ = 110 ... More
Optimal Pricing for Submodular Valuations with Bounded CurvatureNov 23 2016The optimal pricing problem is a fundamental problem that arises in combinatorial auctions. Suppose that there is one seller who has indivisible items and multiple buyers who want to purchase a combination of the items. The seller wants to sell his items ... More
Vacuum type of SU(2) gluodynamics in maximally Abelian and Landau gaugesAug 02 2005The vacuum type of SU(2) gluodynamics is studied using Monte-Carlo simulations in maximally Abelian (MA) gauge and in Landau (LA) gauge, where the dual Meissner effect is observed to work. The dual Meissner effect is characterized by the coherence and ... More
The New Numerical Galaxy Catalog ($ν^2$GC): An Updated Semi-analytic Model of Galaxy and AGN with Large Cosmological N-body SimulationsAug 28 2015We present a new cosmological galaxy formation model, $\nu^2$GC, as the updated version of our previous model $\nu$GC. We adopt the so-called "semi-analytic" approach, in which the formation history of dark matter halos is computed by N-body simulations, ... More
Towards SU(2) invariant formulation of the monopole confinement mechanismSep 22 2005The type of the vacuum is studied numerically in the maximally Abelian (MA) gauge and in the Landau (LA) gauge of SU(2) gluodynamics. The type of the vacuum is determined by a ratio between the dual coherence and the dual penetration lengths. The dual ... More
Magnetic and charge transport properties of the Na-based Os oxide pyrochloreAug 18 2008Na-based osmium oxide pyrochlore was synthesized for the first time by an ion-exchange method. KOs2O6 was used as a host compound. Elelectron probe micro-analysis, synchrotron x-ray diffraction analysis, and thermo-gravimetric analysis confirmed its structure ... More
High-speed observation of the piston effect near the gas-liquid critical pointFeb 08 2006We measured high-speed sound propagation in a near-critical fluid using a ultra-sensitive interferometer to investigate adiabatic changes of fluids on acoustic timescales. A sound emitted by very weak continuous heating caused a stepwise adiabatic change ... More
STM Studies of Isolated Mn12-Ph Single Molecule MagnetsOct 22 2012Nov 08 2012We study Mn12O12(C6H5COO)16(H2O)4 (Mn12-Ph) single-molecule magnets on highly ordered pyrolytic graphite (HOPG) using low temperature scanning tunneling microscopy (LT-STM) experiments. We report Mn12-Ph in isolation, resembling single molecules with ... More
The New Numerical Galaxy Catalog ($ν^2$GC): An Updated Semi-analytic Model of Galaxy and AGN with Large Cosmological N-body SimulationAug 28 2015Oct 22 2016We present a new cosmological galaxy formation model, $\nu^2$GC, as an updated version of our previous model $\nu$GC. We adopt the so-called "semi-analytic" approach, in which the formation history of dark matter halos is computed by ${\it N}$-body simulations, ... More
Crystal Structure of 200 K-Superconducting Phase of Sulfur Hydride SystemSep 10 2015This article reports the experimentally clarified crystal structure of a recently discovered sulfur hydride in high temperature superconducting phase which has the highest critical temperature Tc over 200 K which has been ever reported. For understanding ... More
The electronic state of vortices in YBa2Cu3Oy investigated by complex surface impedance measurementFeb 01 2001Mar 09 2001The electromagnetic response to microwaves in the mixed state of YBa2Cu3Oy(YBCO) was measured in order to investigate the electronic state inside and outside the vortex core. The magnetic-field dependence of the complex surface impedance at low temperatures ... More
Superconducting properties of the oxygen-vacant iron oxyarsenide TbFeAsO1-x from underdoped to overdoped compositionsDec 29 2008Aug 13 2009A wide-range doping was achieved by a high-pressure method for TbFeAsO1-x from "under doped" to "over doped" superconducting compositions throughout the optimized superconductivity (Tc of 44 K). Tc vs. lattice constant shows a dome-shaped feature, while ... More
A Search for deviations from the inverse square law of gravity at nm range using a pulsed neutron beamDec 08 2017We describe an experimental search for deviations from the inverse square law of gravity at the nanometer length scale using neutron scattering from noble gases on a pulsed slow neutron beamline. By measuring the neutron momentum transfer ($q$) dependence ... More
The New Numerical Galaxy Catalogue (ν^2 GC): Properties of Active Galactic Nuclei and Their Host GalaxiesFeb 06 2018We present the latest results of a semi-analytic model of galaxy formation, "New Numerical Galaxy Catalogue", which is combined with large cosmological N-body simulations. This model can reproduce statistical properties of galaxies at z < 6.0. We focus ... More
Synthesis and superconducting properties of the iron oxyarsenide TbFeAsO0.85Aug 14 2008The iron oxyarsenide TbFeAsO0.85 was synthesized by a high-pressure method. A high-quality polycrystalline sample was obtained and characterized by measurements of magnetic susceptibility and electrical resistivity. Bulk superconductivity with Tc of 42 ... More
Pressure-induced Superconductivity in Crystalline Boron NanowiresApr 08 2009We report high-pressure induced superconductivity in boron nanowires (BNWs) with rhombohedral crystal structure. Obviously different from bulk rhombohedral boron, these BNWs show a semiconductor-metal transition at much lower pressure than bulk boron. ... More
Collapse of CuO Double Chains and Suppression of Superconductivity in High-Pressure Phase of YBa$_2$Cu$_4$O$_8$Aug 12 2014The crystal structure and electrical resistivity of YBa$_2$Cu$_4$O$_8$ (Y124) were studied under high pressure up to 18 GPa using diamond-anvil cells, respectively, in order to clarify its conduction mechanism. Y124 causes the first-order phase-transition ... More
Enhancement of the superconducting transition temperature of MgB2 by proximity effect of d0 ferromagnetApr 15 2013Heterostructures of superconducting and ferromagnetic materials are of fundamental interest because of the mutual interaction of antagonistic kinds of ordering at the S-F interface. Normally, the superconducting transition temperature Tc should be strongly ... More
Characterization of Germanium Detectors for the Measurement of the Angular Distribution of Prompt gamma-rays at the ANNRI in the MLF of the J-PARCDec 07 2017In this study, the germanium detector assembly, installed at the Accurate Neutron-Nuclear Reaction measurement Instruments (ANNRI) in the Material and Life Science Facility (MLF) operated by the Japan Proton Accelerator Research Complex (J-PARC), has ... More
Large decrease in the critical temperature of superconducting LaFeAsO0.85 compounds doped with 3% atomic weight of nonmagnetic Zn impuritiesJun 15 2010We observed a large decrease of Tc by no more than 3 at.% of Zn doped to the optimized superconductor LaFeAsO0.85 (Tc = 26 K), confirmed by measurements of electrical resistivity, magnetic susceptibility, specific heat, M\"ossbauer spectroscopy, Hall ... More
Origin of Pressure-induced Superconducting Phase in K$_{x}$Fe$_{2-y}$Se$_{2}$ studied by Synchrotron X-ray Diffraction and SpectroscopyApr 30 2016Pressure dependence of the electronic and crystal structures of K$_{x}$Fe$_{2-y}$Se$_{2}$, which has pressure-induced two superconducting domes of SC I and SC II, was investigated by x-ray emission spectroscopy and diffraction. X-ray diffraction data ... More
Sr3Co2O6: a possible frustrated spin-chain materialJan 28 2011A dense phase of a post-layered perovskite Sr3Co2O6 was created by a high-pressure and high-temperature synthetic route and quenched to ambient conditions. The structure of Sr3Co2O6 was determined by synchrotron X-ray powder diffraction. Sr3Co2O6 crystallizes ... More
Current-induced magnetization switching in MgO barrier magnetic tunnel junctions with CoFeB based synthetic ferrimagnetic free layersJan 09 2008We investigated the effect of using a synthetic ferrimagnetic (SyF) free layer in MgO-based magnetic tunnel junctions (MTJs) on current-induced magnetization switching (CIMS), particularly for application to spin-transfer torque random access memory (SPRAM). ... More
Correlation between intercalated magnetic layers and superconductivity in pressurized EuFe2(As0.81P0.19)2Aug 12 2010Nov 22 2015We report comprehensive high pressure studies on correlation between intercalated magnetic layers and superconductivity in EuFe2(As0.81P0.19)2 single crystal through in-situ high pressure resistance, specific heat, X-ray diffraction and X-ray absorption ... More
Drastic suppression of the superconductivity of LaFeAsO0.85 by a nonmagnetic impurityNov 16 2009We observed a drastic Tc suppression caused by no more than 3 at.% of Zn doped to the optimized superconductor LaFeAsO0.85 (Tc = 26 K). The electrical resistivity and magnetic susceptibility measurements suggested that it is likely due to impurity scatterings ... More
Precise neutron lifetime experiment using pulsed neutron beams at J-PARCFeb 10 2017The neutron lifetime is one of the basic parameters in the weak interaction, and is used for predicting the light element abundance in the early universe. Our group developed a new setup to measure the lifetime with the goal precision of 0.1% at the polarized ... More
Ba2NiOsO6: A Dirac-Mott insulator with ferromagnetism near 100 KDec 15 2016The ferromagnetic semiconductor Ba2NiOsO6 (Tmag ~100 K) was synthesized at 6 GPa and 1500 {\deg}C. It crystallizes into a double perovskite structure [Fm-3m; a = 8.0428(1) {\AA}], where the Ni2+ and Os6+ ions are perfectly ordered at the perovskite B-site. ... More
Fundamental physics activities with pulsed neutron at J-PARC(BL05)Dec 18 2017Jan 25 2018"Neutron Optics and Physics (NOP/ BL05)" at MLF in J-PARC is a beamline for studies of fundamental physics. The beamline is divided into three branches so that different experiments can be performed in parallel. These beam branches are being used to develop ... More
The status of KAGRA underground cryogenic gravitational wave telescopeOct 13 2017KAGRA is a 3-km interferometric gravitational wave telescope located in the Kamioka mine in Japan. It is the first km-class gravitational wave telescope constructed underground to reduce seismic noise, and the first km-class telescope to use cryogenic ... More