Results for "Shogo Nishiyama"

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Impact of distance determinations on Galactic structure. I. Young and intermediate-age tracersApr 13 2018Here we discuss impacts of distance determinations on the Galactic disk traced by relatively young objects. The Galactic disk, about 40 kpc in diameter, is a cross-road of studies on the methods of measuring distances, interstellar extinction, evolution ... More
Young, Massive Star Candidates Detected throughout the Nuclear Star Cluster of the Milky WayOct 23 2012Aims. Young, massive stars have been found at projected distances R < 0.5 pc from supermassive black hole, Sgr A* at the center of our Galay. In recent years, increasing evidence has been found for the presence of young, massive stars also at R > 0.5 ... More
Near-IR Imaging Polarimetry toward a Bright-Rimmed Cloud: Magnetic Field in SFO 74Nov 07 2014We have made near-infrared (JHKs) imaging polarimetry of a bright-rimmed cloud (SFO 74). The polarization vector maps clearly show that the magnetic field in the layer just behind the bright rim is running along the rim, quite different from its ambient ... More
The efficiency and wavelength dependence of near-infrared interstellar polarization toward the Galactic centerMar 03 2013Near-infrared polarimetric imaging observations toward the Galactic center have been carried out to examine the efficiency and wavelength dependence of interstellar polarization. A total area of about 5.7 deg$^2$ is covered in the $J$, $H$, and $K_S$ ... More
PSU(2,2|4) Exchange Algebra of N=4 Superconformal MultipletsDec 25 2014It is known that the unitary representation of the D=4, N=4 superconformal multiplets and their descendants are constructed as supercoherent states of bosonic and fermionic creation oscillators which covariantly transform under SU(2,2|4). We non-linearly ... More
Killing scalar of non-linear sigma models on G/H realizing the classical exchange algebraMay 19 2014Jul 13 2014The Poisson brackets for non-linear sigma models on G/H are set up on the light-like plane. A quantity which transforms irreducibly by the Killing vectors, called Killing scalar, is constructed in an arbitrary representation of G. It is shown to satisfy ... More
Classical Exchange Algebra of the Superstring on S^5 with the AdS-timeSep 25 2007May 21 2014A classical exchange algebra of the superstring on S^5 with the AdS-time is shown on the light-like plane. To this end we use the geometrical method of which consistency is guaranteed by the classical Yang-Baxter equation. The Dirac method does not work, ... More
Top-antitop charge asymmetry measurements in the dilepton channel with the ATLAS detectorJan 14 2019We report a measurement of the charge asymmetry $A_C$ in top quark pair production with the ATLAS experiment. The measurement focuses on dilepton channels ($ee$, $e\mu$, $\mu\mu$). The data are unfolded to parton level at full phase space using a fully ... More
Photon detection operator and complementarity between electric detector and magnetic detectorSep 03 2013Nov 21 2013It had been a long standing problem that there is no consistent definition of photon position operator nor photon number density in the context of quantum theory. In this paper we derive the photon detection operator, which defines location of photon ... More
Superselection Rules from Measurement TheoryDec 24 2011In quantum theory, physically measurable quantities of a microscopic system are represented by self-adjoint operators. However, not all of the self-adjoint operators correspond to measurable quantities. The superselection rule is a criterion to distinguish ... More
Path Integrals on Riemannian Manifolds with Symmetry and Induced Gauge StructureJun 20 2000Jan 16 2001We formulate path integrals on any Riemannian manifold which admits the action of a compact Lie group by isometric transformations. We consider a path integral on a Riemannian manifold M on which a Lie group G acts isometrically. Then we show that the ... More
Topology and Inequivalent Quantizations of Abelian Sigma ModelFeb 28 1995The abelian sigma model in (1+1) dimensions is a field theoretical model which has a field $ \phi : S^1 \to S^1 $. An algebra of the quantum field is defined respecting the topological aspect of the model. It is shown that the zero-mode has an infinite ... More
Quantum Mechanics on ManifoldsJun 28 1993A definition of quantum mechanics on a manifold $ M $ is proposed and a method to realize the definition is presented. This scheme is applicable to a homogeneous space $ M = G / H $. The realization is a unitary representation of the transformation group ... More
Uncertainty relation between angle and orbital angular momentum: interference effect in electron vortex beamsNov 04 2014Apr 06 2015The uncertainty relation between angle and orbital angular momentum had not been formulated in a similar form as the uncertainty relation between position and linear momentum because the angle variable is not represented by a quantum mechanical self-adjoint ... More
More on the Triplet Killing Potentials of Quaternionic Kaehler ManifoldsJun 29 2005We show the properties of the triplet Killing potentials of quaternionic Kaehler manifolds which have been missing in the literature. It is done by means of the metric formula of the manifolds. We compute the triplet Killing potentials for the quaternionic ... More
Apparent Superluminal Muon-neutrino Velocity as a Manifestation of Weak ValueOct 09 2011The result of the OPERA experiment revealed that the velocity of muon-neutrinos was larger than the speed of light. We argue that this apparent superluminal velocity can be interpreted as a weak value, which is a new concept recently studied in the context ... More
Gauge Field, Parity and Uncertainty Relation of Quantum Mechanics on S^1Jun 21 1993We consider the uncertainty relation between position and momentum of a particle on $ S^1 $ (a circle). Since $ S^1 $ is compact, the uncertainty of position must be bounded. Consideration on the uncertainty of position demands delicate treatment. Recently ... More
Complementarity and the nature of uncertainty relations in Einstein-Bohr recoiling slit experimentMar 14 2007Jul 16 2015A model of the Einstein-Bohr double-slit experiment is formulated in a fully quantum theoretical setting. In this model, the state and dynamics of a movable wall that has the double slits in it, as well as the state of a particle incoming to the double ... More
Quantization on a torus without position operatorsSep 09 2003Oct 11 2003We formulate quantum mechanics in the two-dimensional torus without using position operators. We define an algebra with only momentum operators and shift operators and construct irreducible representation of the algebra. We show that it realizes quantum ... More
Zero-mode, Winding Number and Quantization of Abelian Sigma Model in (1+1) DimensionsDec 20 1994We consider the $ U(1) $ sigma model in the two dimensional space-time which is a field-theoretical model possessing a nontrivial topology. It is pointed out that its topological structure is characterized by the zero-mode and the winding number. A new ... More
Isoholonomic Problem and Holonomic Quantum ComputationMay 06 2005Geometric phases accompanying adiabatic processes in quantum systems can be utilized as unitary gates for quantum computation. Optimization of control of the adiabatic process naturally leads to the isoholonomic problem. The isoholonomic problem in a ... More
Path Integrals on Riemannian Manifolds with Symmetry and Stratified Gauge StructureOct 02 2001We study a quantum system in a Riemannian manifold M on which a Lie group G acts isometrically. The path integral on M is decomposed into a family of path integrals on a quotient space Q=M/G and the reduced path integrals are completely classified by ... More
A distribution for a pair of unit vectors generated by Brownian motionSep 07 2009We propose a bivariate model for a pair of dependent unit vectors which is generated by Brownian motion. Both marginals have uniform distributions on the sphere, while the conditionals follow so-called ``exit'' distributions. Some properties of the proposed ... More
Near-infrared Polarimetry toward the Galactic Center - Magnetic Field Configuration in the Central One Degree Region -Jan 29 2010We present a NIR polarimetric map of the 1deg by 1deg region toward the Galactic center. Comparing Stokes parameters between highly reddened stars and less reddened ones, we have obtained a polarization originating from magnetically aligned dust grains ... More
Intrinsically Polarized Stars and Implication for Star Formation in the Central Parsec of Our GalaxyOct 11 2013We have carried out adaptive-optics assisted observations at the Subaru telescope, and have found 11 intrinsically polarized sources in the central parsec of our Galaxy. They are selected from 318 point sources with Ks<15.5, and their interstellar polarizations ... More
The Infrared Counterpart of the X-Ray Nova XTE J1720-318Nov 30 2003We report on the discovery of an infrared counterpart to the X-ray transient XTE J1720-318 on 2003 January 18, nine days after an X-ray outburst, and the infrared light curve during the first 130 days after the outburst. The infrared light curve shows ... More
Topology and quantization of abelian sigma model in (1+1) dimensionsAug 17 1994It is known that there exist an infinite number of inequivalent quantizations on a topologically nontrivial manifold even if it is a finite-dimensional manifold. In this paper we consider the abelian sigma model in (1+1) dimensions to explore a system ... More
The Berkovits Method for Conformally Invariant Non-linear Sigma-models on G/HFeb 21 2006We discuss 2-dimmensional non-linear sigma-models on the Kaehler manifold G/H in the first order formalisim. Using the Berkovits method we explicitly construct the G-symmetry currents and primaries, when G/H are irreducible. It is a variant of the Wakimoto ... More
The Disc Amplitude of the Dijkgraaf-Vafa Theory:1/N Expansion vs Complex Curve AnalysisApr 20 2005May 02 2005According to Dijkgraaf and Vafa the effective glueball superpotential of the N=1 supersymmetric QCD coupled with an adjoint chiral multiplet is given by the planar amplitude in the 1/N expansion of a matrix model. It was shown that, when the N=1 supersymmetric ... More
Algebra and Twisted Algebra in Toroidal Target SpaceJan 16 1996Mar 01 1996Target space duality is reconsidered from the viewpoint of quantization in a space with nontrivial topology. An algebra of operators for the toroidal bosonic string is defined and its representations are constructed. It is shown that there exist an infinite ... More
Entropy production in 2D $λφ^4$ theory in the Kadanoff-Baym approachOct 28 2008Jan 13 2010We study non-equilibrium quantum dynamics of the single-component scalar field theory in 1+1 space-time dimensions on the basis of the Kadanoff-Baym equation including the next-to-leading-order (NLO) skeleton diagrams. As an extension of the non-relativistic ... More
Remarks on the asymptotic behavior of the solution of an abstract damped wave equationMay 06 2015Sep 30 2015We study an abstract damped wave equation. We prove that the solution of the damped wave equation becomes closer to the solution of a heat type equation as time tend to infinity. As an application of our approach, we also study the asymptotic behavior ... More
Universal critical behavior of the two-magnon-bound-state mass gap for the (2+1)-dimensional Ising modelJul 31 2014The two-magnon-bound-state mass gap m_2 for the two-dimensional quantum Ising model was investigated by means of the numerical diagonalization method; the low-lying spectrum is directly accessible via the numerical diagonalization method. It has been ... More
Transfer-matrix approach to the three-dimensional bond percolation: An application of Novotny's formalismDec 18 2005A transfer-matrix simulation scheme for the three-dimensional (d=3) bond percolation is presented. Our scheme is based on Novotny's transfer-matrix formalism, which enables us to consider arbitrary (integral) number of sites N constituting a unit of the ... More
Stiffening of fluid membranes due to thermal undulations: density matrix renormalization group studyOct 22 2002It has been considered that the effective bending rigidity of fluid membranes should be reduced by thermal undulations. However, recent thorough investigation by Pinnow and Helfrich revealed significance of measure factors for the partition sum. Accepting ... More
Deconfined criticality for the two-dimensional quantum S=1-spin model with the three-spin and biquadratic interactionsMar 28 2015The criticality between the nematic and valence-bond-solid (VBS) phases was investigated for the two-dimensional quantum S=1-spin model with the three-spin and biquadratic interactions by means of the numerical diagonalization method. It is expected that ... More
Criticality of the (2+1)-dimensional S=1 transverse-field Ising model with extended interactions: Suppression of corrections to scalingMar 09 2010The criticality of the (2+1)-dimensional S=1 transverse-field Ising model is investigated with the numerical diagonalization method. The scaling behavior is improved by tuning the coupling-constant parameters; the S=1 spin model allows us to incorporate ... More
Properties of discrete Fisher information: Cramer-Rao-type and log-Sobolev-type inequalitiesApr 29 2019The Fisher information have connections with the standard deviation and the Shannon differential entropy through the Cramer-Rao bound and the log-Sobolev inequality. These inequalities hold for continuous distributions. In this paper, we introduce the ... More
Inequalities between $L^p$-norms for log-concave distributionsMar 25 2019Log-concave distributions include some important distributions such as normal distribution, exponential distribution and so on. In this note, we show inequalities between two Lp-norms for log-concave distributions on the Euclidean space. These inequalities ... More
$L^p$-norm inequality using q-moment and its applicationsFeb 04 2019Feb 20 2019For a measurable function on a set which has a finite measure, an inequality holds between two Lp-norms. In this paper, we show similar inequalities for the Euclidean space and the Lebesgue measure by using a q-moment which is a moment of an escort distribution. ... More
Asymptotic cone of semisimple orbits for symmetric pairsDec 15 2010Let G be a reductive algebraic group over the complex field and O_h be a closed adjoint orbit through a semisimple element h. By a result of Borho and Kraft (1979), it is known that the asymptotic cone of the orbit O_h is the closure of a Richardson nilpotent ... More
Resolution of null fiber and conormal bundles on the Lagrangian GrassmannianJan 26 2007Dec 28 2007We study the null fiber of a moment map related to dual pairs. We construct an equivariant resolution of singularities of the null fiber, and get conormal bundles of closed $ K_C $-orbits in the Lagrangian Grassmannian as the categorical quotient. The ... More
The Age and Metallicity Dependence of the Near-Infrared Magnitudes of Red Clump StarsApr 29 2019Red clump (RC) stars are widely used as an excellent standard candle. To make them even better, it is important to know the dependence of their absolute magnitudes on age and metallicity. We observed star clusters in the Large Magellanic Cloud to fill ... More
YSO search toward the boundary of the Central Molecular Zone with near-infrared polarimetryJun 11 2014We have carried out near-infrared polarimetry toward the boundary of the Central Molecular Zone, in the field of (-1.4 deg $\lesssim l \lesssim$ -0.3 deg and 1.0 deg $\lesssim l \lesssim$ 2.9 deg, $|b|\lesssim$ 0.1 deg), using the near-infrared polarimetric ... More
Deconfined-critical behavior of the VBS- and nematic-order parameters for the spatially anisotropic S=1-spin modelAug 23 2012The phase transition between the valence-bond-solid (VBS) and nematic phases, the so-called deconfined criticality, was investigated for the quantum S=1-spin model on the spatially anisotropic triangular lattice with the biquadratic interaction by means ... More
d=2 transverse-field Ising model under the screw-boundary condition: An optimization of the screw pitchSep 02 2011A length-N spin chain with the \sqrt{N}(=v)-th neighbor interaction is identical to a two-dimensional (d=2) model under the screw-boundary (SB) condition. The SB condition provides a flexible scheme to construct a d\ge2 cluster from an arbitrary number ... More
Crumpling transition of the discrete planar folding in the negative-bending-rigidity regimeJul 13 2010The folding of the triangular lattice embedded in two dimensions (discrete planar folding) is investigated numerically. As the bending rigidity K varies, the planar folding exhibits a series of crumpling transitions at K \approx -0.3 and K \approx 0.1. ... More
Numerical diagonalization analysis of the criticality of the (2+1)-dimensional XY model: Off-diagonal Novotny's methodAug 27 2008The criticality of the (2+1)-dimensional XY model is investigated with the numerical diagonalization method. So far, it has been considered that the diagonalization method would not be very suitable for analyzing the criticality in large dimensions (d ... More
Multicriticality of the (2+1)-dimensional gonihedric model: A realization of the (d,m)=(3,2) Lifshitz pointApr 30 2007Multicriticality of the gonihedric model in 2+1 dimensions is investigated numerically. The gonihedric model is a fully frustrated Ising magnet with the finely tuned plaquette-type (four-body and plaquette-diagonal) interactions, which cancel out the ... More
Folding of the triangular lattice in a discrete three-dimensional space: Crumpling transitions in the negative-bending-rigidity regimeAug 12 2005Folding of the triangular lattice in a discrete three-dimensional space is studied numerically. Such ``discrete folding'' was introduced by Bowick and co-workers as a simplified version of the polymerized membrane in thermal equilibrium. According to ... More
Folding of the triangular lattice in a discrete three-dimensional space: Density-matrix-renormalization-group studyMar 31 2004Folding of the triangular lattice in a discrete three-dimensional space is investigated numerically. Such ``discrete folding'' has come under through theoretical investigation, since Bowick and co-worker introduced it as a simplified model for the crumpling ... More
Quantum-fluctuation-induced collisions and subsequent excitation gap of an elastic string between wallsFeb 18 2002An elastic string embedded between rigid walls is simulated by means of the density-matrix renormalization group. The string collides against the walls owing to the quantum-mechanical zero-point fluctuations. Such ``quantum entropic'' interaction has ... More
Numerical analyses of the nonequilibrium electron transport through the Kondo impurity beside the Toulouse pointFeb 23 2000Nonequilibrium electron transport through the Kondo impurity is investigated numerically for the system with twenty conduction-electron levels. The electron current under finite voltage drop is calculated in terms of the `conductance viewed as transmission' ... More
Universal scaled Higgs-mass gap for the bilayer Heisenberg model in the ordered phaseJan 19 2016The spectral properties for the bilayer quantum Heisenberg model were investigated with the numerical diagonalization method. In the ordered phase, there appears the massive Higgs excitation embedded in the continuum of the Goldstone excitations. Recently, ... More
Neel-VBS phase boundary of the extended J_1-J_2 model with biquadratic interactionJan 04 2012The J_1-J_2 model with the biquadratic (plaquette-four-spin) interaction was simulated with the numerical-diagonalization method. Some limiting cases of this model have been investigated thoroughly. Taking the advantage of the extended parameter space, ... More
Random-field-driven phase transitions in the ground state of the S=1 XXZ spin chainMay 10 1998Ground-state of the S=1 XXZ spin chain under the influence of the random magnetic field is studied by means of the exact-diagonalization method. The S=1/2 counterpart has been investigated extensively so far. The easy-plane area, including the Haldane ... More
On the paper ``Weak convergence of some classes of martingales with jumps''Jul 31 2007This note extends some results of Nishiyama [Ann. Probab. 28 (2000) 685--712]. A maximal inequality for stochastic integrals with respect to integer-valued random measures which may have infinitely many jumps on compact time intervals is given. By using ... More
Improved Chebyshev inequality: new probability bounds with known supremum of PDFAug 31 2018Sep 07 2018In this paper, we derive new probability bounds for Chebyshev's inequality if the supremum of the probability density function is known. This result holds for one-dimensional or multivariate continuous probability distributions with finite mean and variance ... More
Divergence functions in dually flat spaces and their propertiesAug 16 2018Sep 08 2018In the field of statistics, many kind of divergence functions have been studied as an amount which measures the discrepancy between two probability distributions. In the differential geometrical approach in statistics (information geometry), dually flat ... More
A stochastic maximal inequality, strict countability, and infinite-dimensional martingalesJul 27 2017Aug 15 2017As an alternative to the well-known methods of "chaining" and "bracketing" that have been developed in the study of random fields, a new method, which is based on a {\em stochastic maximal inequality} derived by using the formula for integration by parts ... More
Enhanced orbit embeddingOct 09 2014Nov 23 2014Let $ \tilde{G} $ be an algebraic group acting on a variety $ \tilde{L} $, and $ G \subset \tilde{G} $ a subgroup which leaves a subvariety $ L \subset \tilde{L} $ stable. For a $ G $-orbit $ O_G = G u (u \in L) $ in $ L $, we can associate an orbit $ ... More
Criticalities of the transverse- and longitudinal-field fidelity susceptibilities for the d=2 quantum Ising modelJul 13 2013The inner product between the ground-state eigenvectors with proximate interaction parameters, namely, the fidelity, plays a significant role in the quantum dynamics. In this paper, the critical behaviors of the transverse- and longitudinal-field fidelity ... More
Critical behavior of the fidelity susceptibility for the d=2 transverse-field Ising modelMay 17 2013The overlap (inner product) between the ground-state eigenvectors with proximate interaction parameters, the so-called fidelity, plays a significant role in the quantum-information theory. In this paper, the critical behavior of the fidelity susceptibility ... More
Crumpling transition of the triangular lattice without open edges: effect of a modified folding ruleMar 10 2010Folding of the triangular lattice in a discrete three-dimensional space is investigated by means of the transfer-matrix method. This model was introduced by Bowick and co-workers as a discretized version of the polymerized membrane in thermal equilibrium. ... More
Deconfinement criticality for the spatially anisotropic triangular antiferromagnet with the ring exchangeFeb 12 2009The spatially anisotropic triangular antiferromagnet is investigated with the numerical diagonalization method. As the anisotropy varies, the model changes into a variety of systems such as the one-dimensional, triangular, and square-lattice antiferromagnets. ... More
Bound-state energy of the d=3 Ising model in the broken-symmetry phase: Suppressed finite-size correctionsApr 09 2008The low-lying spectrum of the three-dimensional Ising model is investigated numerically; we made use of an equivalence between the excitation gap and the reciprocal correlation length. In the broken-symmetry phase, the magnetic excitations are attractive, ... More
Quantum-fluctuation-induced repelling interaction of quantum string between wallsFeb 07 2001Quantum string, which was brought into discussion recently as a model for the stripe phase in doped cuprates, is simulated by means of the density-matrix-renormalization-group method. String collides with adjacent neighbors, as it wonders, owing to quantum ... More
Revisiting Unit Fractions That Sum To 1Mar 23 2016This paper is a continuation of a previous paper. Here, as there, we examine the problem of finding the maximum number of terms in a partial sequence of distinct unit fractions larger than 1/100 that sums to 1. In the previous paper, we found that the ... More
Finite-size-scaling analysis of the XY universality class between two and three dimensions: An application of Novotny's transfer-matrix methodFeb 03 2005Based on Novotny's transfer-matrix method, we simulated the (stacked) triangular Ising antiferromagnet embedded in the space with the dimensions variable in the range 2 \le d \le 3. Our aim is to investigate the criticality of the XY universality class ... More
Multi-criticality of the three-dimensional Ising model with plaquette interactions: An extension of Novotny's transfer-matrix formalismJul 12 2004Three-dimensional Ising model with the plaquette-type (next-nearest-neighbor and four-spin) interactions is investigated numerically. This extended Ising model, the so-called gonihedric model, was introduced by Savvidy and Wegner as a discretized version ... More
Electron trajectory in the hydrogen atomOct 10 2001Dec 27 2001A trajectory in the Schroedinger wave for an electron in an attractive Coulomb potential with the dynamical behavior is proposed and illustrated for a scattering and a bound state. The scattering cross section derived from the trajectories is almost exactly ... More
Numerical analysis of the dissipative two-state system with the density-matrix Hilbert-space-reduction algorithmApr 19 1999Ground state of the dissipative two-state system is investigated by means of the Lanczos diagonalization method. We adopted the Hilbert-space-reduction scheme proposed by Zhang, Jeckelmann and White so as to reduce the overwhelming reservoir Hilbert space ... More
Numerical diagonalization analysis of the ground-state superfluid-localization transition in two dimensionsDec 20 1998Ground state of the two-dimensional hard-core-boson system in the presence of the quenched random chemical potential is investigated by means of the exact-diagonalization method for the system sizes up to L=5. The criticality and the DC conductivity at ... More
Criticality of the Higgs mass for the long-range quantum $XY$ chain: Amplitude ratio between the Higgs and paramagnetic gapsMay 12 2019The quantum $XY$ spin chain with the interactions decaying as a power law $1/r^{1+ \sigma}$ of the distance between spins $r$ was investigated with the exact diagonalization method. Here, the constituent spin is set to $S=1$, which enables us to incorporate ... More
A remark on the Schrödinger equation on Zoll manifoldsMar 27 2011On the one dimensional sphere, the support of the fundamental solution to the Schr$\rm \ddot o$dinger equation consists of finite points at the time $t\in 2\pi\Q$. The paper \cite{Ka} generalized this fact to compact symmetric spaces. In this paper, we ... More
Magnon-bound-state hierarchy for the two-dimensional transverse-field Ising model in the ordered phaseJul 30 2016In the ordered phase for an Ising ferromagnet, the magnons are attractive to form a series of bound states with the mass gaps, $m_2<m_3 < \dots$. Each ratio $m_{2,3,\dots}/m_1$ ($m_1$: the single-magnon mass) is expected to be a universal constant in ... More
Finite-size scaling of the d=5 Ising model embedded in the cylindrical geometry: An influence of the hyperscaling violationNov 30 2006Finite-size scaling (FSS) of the five-dimensional (d=5) Ising model is investigated numerically. Because of the hyperscaling violation in d>4, FSS of the d=5 Ising model no longer obeys the conventional scaling relation. Rather, it is expected that the ... More
Strong-coupling-expansion analysis of the false-vacuum decay rate of the lattice phi^4 model in 1+1 dimensionsOct 10 2001Strong-coupling expansion is performed for the lattice phi^4 model in 1+1 dimensions. Because the strong-coupling limit itself is not solvable, we employed numerical calculations so as to set up unperturbed eigensystems. Restricting the number of Hilbert-space ... More
Numerical analysis of the magnetic-field-tuned superconductor-insulator transition in two dimensionsNov 01 2000Ground state of the two-dimensional hard-core-boson model subjected to external magnetic field and quenched random chemical potential is studied numerically. In experiments, magnetic-field-tuned superconductor-insulator transition has already come under ... More
Direct observation of the effective bending moduli of a fluid membrane: Free-energy cost due to the reference-plane deformationsJul 10 2003Effective bending moduli of a fluid membrane are investigated by means of the transfer-matrix method developed in our preceding paper. This method allows us to survey various statistical measures for the partition sum. The role of the statistical measures ... More
Finite-size-scaling analyses of the chiral order in the Josephson-junction ladder with half a flux quantum per plaquetteJun 21 2000Chiral order of the Josephson-junction ladder with half a flux quantum per plaquette is studied by means of the exact diagonalization method. We consider an extreme quantum limit where each superconductor grain (order parameter) is represented by S=1/2 ... More
Sum decomposition of divergence into three divergencesOct 03 2018Oct 06 2018Divergence functions play a key role as to measure the discrepancy between two points in the field of machine learning, statistics and signal processing. Well-known divergences are the Bregman divergences, the Jensen divergences and the f-divergences. ... More
Generalized Bregman and Jensen divergences which include some f-divergencesAug 19 2018Sep 20 2018In this paper, we introduce new classes of divergences by extending the definitions of the Bregman divergence and the skew Jensen divergence. These new divergence classes (g-Bregman divergence and skew g-Jensen divergence) satisfy some properties similar ... More
Cramér-Rao-type Bound and Stam's Inequality for Discrete Random VariablesApr 29 2019May 19 2019The variance and the entropy power of a continuous random variable are bounded from below by the reciprocal of its Fisher information through the Cram\'{e}r-Rao bound and the Stam's inequality respectively. In this note, we introduce the Fisher information ... More
Critical behavior of the Higgs- and Goldstone-mass gaps for the two-dimensional S=1 XY modelJun 12 2015Spectral properties for the two-dimensional quantum S=1 XY model were investigated with the exact diagonalization method. In the symmetry-broken phase, there appear the massive Higgs and massless Goldstone excitations, which correspond to the longitudinal ... More
Deconfined criticality for the S=1 spin model on the spatially anisotropic triangular latticeJan 11 2011The quantum S=1 spin model on the spatially anisotropic triangular lattice is investigated numerically. The nematic and valence-bond-solid (VBS) phases are realized by adjusting the spatial anisotropy and the biquadratic interaction. The phase transition ... More
Eliminated corrections to scaling around a renormalization-group fixed point: Transfer-matrix simulation of an extended d=3 Ising modelJul 01 2006Extending the parameter space of the three-dimensional (d=3) Ising model, we search for a regime of eliminated corrections to finite-size scaling. For that purpose, we consider a real-space renormalization group (RSRG) with respect to a couple of clusters ... More
Trajectory of the harmonic oscillator in the Schreodinger waveSep 14 2001A trajectory of a harmonic oscillator obeying the Schreodinger wave equation is exactly derived and illustrated. The trajectory resembles well the classical orbit between the turning points, and also runs through the tunneling region. The dynamics of ... More
Nonequilibrium-current-induced corrections to the one-particle-correlation function in a wireSep 08 2000Electron gas in a wire connected to two terminals with potential drop is studied with the Schwinger-Keldysh formalism. Recent studies, where the current is enforced to flow with a Lagrange-multiplier term, demonstrated that the current enhances the one-particle-correlation ... More
Numerical Analysis of the Bond-Random Antiferromagnetic S=1 Heisenberg ChainOct 28 1997Ground state of the bond-random antiferromagnetic S=1 Heisenberg chain with the biquadratic interaction -\beta\sum_i(S_i S_i+1)^2 is investigated by means of the exact-diagonalization method and the finite-size-scaling analysis. It is shown that the Haldane ... More
A Sepak Takraw - Based Molecular Model For C60 - A Mathematical Study Of A 60-Atom MoleculeApr 15 2015We mathematically investigate four molecular models of buckminsterfullerene (C60) discussing the strengths and weaknesses of each, and a new orthorhombic 20-dodecahedron model is proposed to replace the traditional truncated icosahedron model. This representation ... More
Divergence Network: Graphical calculation method of divergence functionsOct 30 2018Nov 01 2018In this paper, we introduce directed networks called `divergence network' in order to perform graphical calculation of divergence functions. By using the divergence networks, we can easily understand the geometric meaning of calculation results and grasp ... More
Incomplete Hypergeometric Systems Associated to 1-Simplex $\times$ (n-1)-SimplexDec 17 2010The A-hypergeometric system was introduced by Gel'fand, Kapranov and Zelevinsky in the 1980's. Among several classes of A-hypergeometric functions, those for 1-simplex $\times$ (n-1)-simplex are known to be a very nice class. We will study an incomplete ... More
A New Lower Bound for Kullback-Leibler Divergence Based on Hammersley-Chapman-Robbins BoundJun 29 2019In this paper, we derive a useful lower bound for the Kullback-Leibler divergence (KL-divergence) based on the Hammersley-Chapman-Robbins bound (HCRB). The HCRB states that the variance of an estimator is bounded from below by the Chi-square divergence ... More
A stochastic maximal inequality, strict countability, and related topicsJul 05 2013Feb 10 2016As an alternative to the well-known methods of "chaining" and "bracketing" that have been developed in the study of random fields, a new method, which is based on a stochastic maximal inequality derived by using It\^o's formula and on a new concept named ... More
A note on affine quotients and equivariant double fibrationsJan 26 2007Jan 30 2007We consider two linear reductive algebraic groups $ G $ and $ G' $ over $ C $. Take a finite dimensional rational representation $ W $ of $ G \times G' $. Let $ Y = W // G := Spec C[W]^G $ and $ X = W // G' := \Spec C[W]^{G'} $ be the affine quotients. ... More
Asymptotic theory of semiparametric $Z$-estimators for stochastic processes with applications to ergodic diffusions and time seriesSep 02 2009This paper generalizes a part of the theory of $Z$-estimation which has been developed mainly in the context of modern empirical processes to the case of stochastic processes, typically, semimartingales. We present a general theorem to derive the asymptotic ... More
A method for systematic construction of Bell-like inequalities and a proposal of a new type of testMay 26 2010Jul 01 2010The Bell-Clauser-Horne-Shimony-Holt (BCHSH) inequality, which is proven in the context of the local hidden variable theory, has been used as a test to reveal failure of the hidden variable theory and to prove validity of the quantum theory. We note that ... More
Possible Pairing Symmetry of Three-dimensional Superconductor UPt$_3$ -- Analysis Based on a Microscopic Calculation --Jan 24 2005Stimulated by the anomalous superconducting properties of UPt$_3$, we investigate the pairing symmetry and the transition temperature in the two-dimensional(2D) and three-dimensional(3D) hexagonal Hubbard model. We solve the Eliashberg equation using ... More
The Whitham Deformation of the Dijkgraaf-Vafa TheorySep 25 2003Apr 06 2004We discuss the Whitham deformation of the effective superpotential in the Dijkgraaf-Vafa (DV) theory. It amounts to discussing the Whitham deformation of an underlying (hyper)elliptic curve. Taking the elliptic case for simplicity we derive the Whitham ... More