Results for "Shohei Tamaoki"

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Magnetic stability of massive star forming clumps in RCW 106Apr 12 2019Apr 16 2019The RCW 106 molecular cloud complex is an active massive star-forming region where a ministarburst is taking place. We examined its magnetic structure by near-IR polarimetric observations with the imaging polarimeter SIRPOL on the IRSF 1.4 m telescope. ... More
On explicit random-like tournamentsJan 30 2019We give a new construction of tournaments satisfying the quasi-random property based on digraph spectra and a digraph-version of the expander-mixing lemma. We also discuss an application of our construction to the proof of the NP-hardness of the feedback ... More
A constructive solution to a problem of ranking tournamentsFeb 18 2019A tournament is an oriented complete graph. The problem of ranking tournaments was firstly investigated by P. Erd\H{o}s and J. W. Moon. By probabilistic methods, the existence of "unrankable" tournaments was proved. On the other hand, they also mentioned ... More
On expander Cayley graphs from Galois ringsFeb 09 2019Mar 04 2019In this paper, we study new Cayley graphs over the additive group of Galois rings. First we prove that they are expander graphs by using a Weil-Carlitz-Uchiyama type estimation of character sums for Galois rings. We also show that Cayley graphs from Galois ... More
The orthonormal Strichartz inequality on torusJan 25 2018In this paper, motivated by recent important works due to Frank-Lewin-Lieb-Seiringer \cite{FLLS} and Frank-Sabin \cite{frank-sabin-1}, we study the Strichartz inequality on torus with the orthonormal system input and obtain sharp estimates in certain ... More
Matrix product is many-sorted algebraNov 05 2013It is known that a category of many-sorted algebras on pure sets of similarity type is "concretely equivalent" to a category of single-sorted algebras. In this paper, we characterize a single-sorted variety that corresponds to a many-sorted variety. Such ... More
A "classification" of congruence primal arithmetical algebrasJun 25 2014We classify essential algebras whose irredundant non-refinable covers consist of primal algebras. The proof is obtained by constructing one to one correspondence between such algebras and partial orders on finite sets. Further, we prove that for a finite ... More
Recursive Markov Process for Iterated Games with Markov StrategiesSep 02 2015Apr 27 2018The dynamics in games involving multiple players, who adaptively learn from their past experience, is not yet well understood. We analyzed a class of stochastic games with Markov strategies in which players choose their actions probabilistically. This ... More
Learning LiNGAM based on data with more variables than observationsAug 21 2012A very important topic in systems biology is developing statistical methods that automatically find causal relations in gene regulatory networks with no prior knowledge of causal connectivity. Many methods have been developed for time series data. However, ... More
Joint estimation of linear non-Gaussian acyclic modelsApr 28 2011Nov 30 2011A linear non-Gaussian structural equation model called LiNGAM is an identifiable model for exploratory causal analysis. Previous methods estimate a causal ordering of variables and their connection strengths based on a single dataset. However, in many ... More
Polynomial algorithm for k-partition minimization of submodular system with strong symmetryFeb 06 2018For a fixed $k$, this study considers $k$-partition minimization of submodular system $(V, f)$ with a finite set $V$ and symmetric submodular function $f: 2^{V} \mapsto \mathbb{R}$ with {\it strong symmetry}, which holds $f(U_{0}) = f( U_{1} \setminus ... More
Polynomial algorithm for $k$-partition minimization of monotone submodular functionFeb 06 2018Mar 22 2018For a fixed $k$, this study considers $k$-partition minimization of submodular system $(V, f)$ with a finite set $V$ and symmetric submodular function $f: 2^{V} \mapsto \mathbb{R}$. Our algorithm uses the Queyranne's (1998) algorithm for 2-partition minimization ... More
Magnetic stability of massive star forming clumps in RCW 106Apr 12 2019The RCW~106 molecular cloud complex is an active massive star-forming region where a ministarburst is taking place. We examined its magnetic structure by near-IR polarimetric observations with the imaging polarimeter SIRPOL on the IRSF 1.4 m telescope. ... More
Observable cosmological vector mode in the dark agesJul 14 2016Sep 16 2016The second-order vector mode is inevitably induced from the coupling of first-order scalar modes in cosmological perturbation theory and might hinder a possible detection of primordial gravitational waves from inflation through 21cm lensing observations. ... More
On explicit random-like tournamentsJan 30 2019Feb 15 2019We give a new construction of tournaments satisfying the quasi-random property based on digraph spectra and a digraph-version of the expander-mixing lemma. We also discuss an application of our construction to the proof of the NP-hardness of the feedback ... More
Recursive Markov ProcessSep 02 2015A Markov process, which is constructed recursively, arises in stochastic games with Markov strategies. In this study, we defined a special class of random processes called the recursive Markov process, which has infinitely many states but can be expressed ... More
A note on the relation between two properties of random graphsJan 30 2019The t-existentially closed (t-e.c.) property and pseudo-random property are properties which random graphs asymptotically almost surely satisfy. In this note, by constructing explicit infinite families of graphs without probabilistic arguments, we show ... More
On expander Cayley graphs from Galois ringsFeb 09 2019Feb 15 2019In this paper, we study new Cayley graphs over the additive group of Galois rings. First we prove that they are expander graphs by using a Weil-Carlitz-Uchiyama type estimation of character sums for Galois rings. We also show that Cayley graphs from Galois ... More
General Type Token DistributionMay 02 2013Jun 26 2014We consider the problem of estimating the number of types in a corpus using the number of types observed in a sample of tokens from that corpus. We derive exact and asymptotic distributions for the number of observed types, conditioned upon the number ... More
A note on the relation between two properties of random graphsJan 30 2019Feb 15 2019The t-existentially closed (t-e.c.) property and pseudo-random property are properties which random graphs asymptotically almost surely satisfy. In this note, by constructing explicit infinite families of graphs without probabilistic arguments, we show ... More
Conversion Efficiencies of Heteronuclear Feshbach MoleculesOct 12 2007Feb 10 2008We study the conversion efficiency of heteronuclear Feshbach molecules in population imbalanced atomic gases formed by ramping the magnetic field adiabatically. We extend the recent work [J. E. Williams et al., New J. Phys., 8, 150 (2006)] on the theory ... More
Shil'nikov Chaos control using Homoclinic orbits and the Newhouse regionApr 10 2006A method of controlling Shil'nikov's type chaos using windows that appear in the 1 dimensional bifurcation diagram when perturbations are applied, and using existence of stable homoclinic orbits near the unstable one is presented and applied to the electronic ... More
Dynamic Structure Factor of Normal Fermi Gas from Collisionless to Hydrodynamic RegimeJun 29 2010Oct 02 2010The dynamic structure factor of a normal Fermi gas is investigated by using the moment method for the Boltzmann equation. We determine the spectral function at finite temperatures over the full range of crossover from the collisionless regime to the hydrodynamic ... More
On the Estimation of Pointwise DimensionDec 09 2013Jan 16 2014Our goal in this paper is to develop an effective estimator of fractal dimension. We survey existing ideas in dimension estimation, with a focus on the currently popular method of Grassberger and Procaccia for the estimation of correlation dimension. ... More
Transmission of Excitations in a Spin-1 Bose-Einstein Condensate through a BarrierMar 05 2011May 11 2011We investigate tunneling of excitations across a potential barrier separating two spin-1 Bose-Einstein condensates. Using the mean-field theory at the absolute zero temperature, we determine transmission coefficients of excitations in the saturated magnetization ... More
Effects of the tilted and wavy current sheet on the solar modulation of galactic cosmic raysOct 26 2006Transport equation of the galactic cosmic ray (GCR) is numerically solved for qA>0 and qA<0 based on the stochastic differential equation (SDE) method. We have developed a fully time-dependent and three-dimensional code adapted for the wavy heliospheric ... More
Weighted norm inequalities on Morrey spacesJun 03 2016In this paper, we shall investigate weighted Morrey spaces by employing the sparse family. Particularly, we shall discuss the boundedness of the Hardy-Littlewood maximal operator and the singular integral operators on weighted Morrey spaces. In addition, ... More
Green's function formalism for a condensed Bose gas consistent with infrared-divergent longitudinal susceptibility and Nepomnyashchii-Nepomnyashchii identityFeb 28 2014Jun 13 2014We present a Green's function formalism for an interacting Bose-Einstein condensate (BEC) satisfying the two required conditions: (i) the infrared-divergent longitudinal susceptibility with respect to the BEC order parameter, and (ii) the Nepomnyashchii-Nepomnyashchii ... More
Charge-breaking constraints on left-right mixing of stau'sNov 01 2010Nov 23 2012In the minimal supersymmetric standard model, large left-right mixing of stau's is sometimes intriguing from phenomenological viewpoints. However, too large left-right mixing is not acceptable since the electroweak-breaking vacuum becomes metastable. ... More
Multiple Populations of Extrasolar Gas GiantsMar 13 2019Mar 14 2019There are two planetary formation scenarios: core accretion and gravitational disk instability. Based on the fact that gaseous objects are preferentially observed around metal-rich host stars, most extra-solar gaseous objects discovered to date are thought ... More
Reflection and Refraction of Bose-condensate ExcitationsFeb 26 2008Aug 08 2008We investigate the transmission and reflection of Bose-condensate excitations in the low energy limit across a potential barrier separating two condensates with different densities. The Bogoliubov excitation in the low energy limit has the incident angle ... More
Dynamical Density Fluctuation of Superfluids near Critical VelocitiesJun 15 2010We propose a stability criterion of superfluids in condensed Bose-Einstein systems, which incorporates the spectral function or the autocorrelation function of the local density. Within the Gross-Pitaevskii-Bogoliubov theory, we demonstrate the validity ... More
Bayesian estimation of possible causal direction in the presence of latent confounders using a linear non-Gaussian acyclic structural equation model with individual-specific effectsOct 24 2013May 20 2014We consider learning the possible causal direction of two observed variables in the presence of latent confounding variables. Several existing methods have been shown to consistently estimate causal direction assuming linear or some type of nonlinear ... More
Radiation feedback in dusty cloudsMay 09 2016We have investigated the impact of photoionization and radiation pressure on a dusty star-forming cloud by one-dimensional radiation hydrodynamic simulations, which include absorption and re-emission of photons by dust. We find that even in a moderately ... More
The behaviour of curvature functions at cusps and inflection pointsFeb 22 2011At a 3/2-cusp of a given plane curve $\gamma(t)$, both of the Euclidean curvature $\kappa_g$ and the affine curvature $\kappa_A$ diverge. In this paper, we show that each of $\sqrt{|s_g|}\kappa_g$ and $(s_A)^2 \kappa_A$ (called the Euclidean and affine ... More
Comparative studies of many-body corrections to an interacting Bose condensateAug 31 2013Nov 18 2013We compare many-body theories describing fluctuation corrections to the mean-field theory in a weakly interacting Bose-condensed gas. Using a generalized random-phase approximation, we include both density fluctuations and fluctuations in the particle-particle ... More
Stability Criterion for Superfluidity based on the Density Spectral FunctionMay 30 2013Dec 04 2013We study a stability criterion hypothesis for superfluids in terms of the the local density spectral function $I_n (r, \omega)$ applicable both to homogeneous and inhomogeneous systems. We evaluate the local density spectral function in the presence of ... More
Anomalous Scattering of Low-lying Excitations in a Spin-1 Bose-Einstein CondensateDec 27 2010We present the simplest theory of perfect tunneling of an excitation in a Bose-Einstein condensate (BEC) through an impurity potential with an arbitrary shape in the low-momentum limit. That is for the transverse spin wave in the ferromagnetic phase of ... More
Transmission and Reflection of Collective Modes in Spin-1 Bose-Einstein CondensateSep 14 2009We study tunneling properties of collective excitations in spin-1 Bose-Einstein condensates. In the absence of magnetic fields, the total transmission in the long wavelength limit occurs in all kinds of excitations but the quadrupolar spin mode in the ... More
Combining Linear Non-Gaussian Acyclic Model with Logistic Regression Model for Estimating Causal Structure from Mixed Continuous and Discrete DataFeb 16 2018Estimating causal models from observational data is a crucial task in data analysis. For continuous-valued data, Shimizu et al. have proposed a linear acyclic non-Gaussian model to understand the data generating process, and have shown that their model ... More
A New Method for Calibration of Gain Variation in Detector SystemOct 23 2018Oct 24 2018Transit spectroscopy of habitable planets orbiting late-type stars requires high relative spectro-photometric accuracy between wavelengths during transit/eclipse observation. The spectro-photometric signal is not affected only by image movement and deformation ... More
The singular integral operator and its commutator on weighted Morrey spacesJun 03 2016Oct 17 2016In this paper, we give necessary conditions and sufficient conditions respectively for the boundedness of the singular integral operator on the weighted Morrey spaces. We observe the phenomenon unique to the case of Morrey spaces; the $A_q$-theory by ... More
Effects of axions on Nucleosynthesis in massive starsFeb 09 2015We investigate the effect of the axion cooling on the nucleosynthesis in a massive star with $16M_{\odot}$ by standard stellar evolution calculation. We find that the axion cooling suppresses the nuclear reactions in carbon, oxygen and silicon burning ... More
Upper limit on the amplitude of gravitational waves around 0.1Hz from the Global Positioning SystemFeb 18 2014The global positioning system (GPS) is composed of thirty one satellites having atomic clocks with $10^{-15}$ accuracy on board and enables one to calibrate the primary standard for frequency on the ground. Using the fact that oscillators on the ground ... More
A direct method for estimating a causal ordering in a linear non-Gaussian acyclic modelAug 09 2014Structural equation models and Bayesian networks have been widely used to analyze causal relations between continuous variables. In such frameworks, linear acyclic models are typically used to model the datagenerating process of variables. Recently, it ... More
Galactic modulation of extragalactic cosmic rays: Possible origin of the knee in the cosmic ray spectrumFeb 07 2005Feb 09 2005The existence of the spectral break around $\sim 3 \times 10^{15}$ eV in the cosmic ray spectrum (referred to as the `knee') is one of the biggest questions in cosmic ray astrophysics. At the same time, the origin of cosmic rays above the knee energies ... More
Constraining primordial vector mode from B-mode polarizationMay 19 2014Sep 11 2014The B-mode polarization spectrum of the Cosmic Microwave Background (CMB) may be the smoking gun of not only the primordial tensor mode but also of the primordial vector mode. If there exist nonzero vector-mode metric perturbations in the early Universe, ... More
Parity violation in the CMB bispectrum by a rolling pseudoscalarAug 30 2013Nov 21 2013We investigate parity-violating signatures of temperature and polarization bispectra of the cosmic microwave background (CMB) in an inflationary model where a rolling pseudoscalar produces large equilateral tensor non-Gaussianity. By a concrete computation ... More
Flavor structure in D-brane models: Majorana neutrino massesFeb 10 2014Jun 11 2014We study the flavor structure in intersecting D-brane models. We study anomalies of the discrete flavor symmetries. We analyze the Majorana neutrino masses, which can be generated by D-brane instanton effects. It is found that a certain pattern of mass ... More
Numerical studies on the structure of the cosmic ray electron halo in starburst galaxiesOct 26 2006The structure of the cosmic ray electron halo of a starburst galaxy depends strongly on the nature of galactic wind and the configuration of the magnetic field. We have investigated these dependencies by solving numerically the propagation of electrons ... More
Poly-instanton axion inflationMay 11 2017We investigate the axion inflation model derived by poly-instanton effects in type II superstring theories. Poly-instanton effects are instanton effects corrected by another instanton and it can generate the modulus-axion potential with the double exponential ... More
Relaxation to Gaussian Generalized Gibbs Ensembles in Exactly Solvable Bosonic Systems in the Thermodynamic LimitMar 01 2019Integrable quantum many-body systems are considered to equilibrate to generalized Gibbs ensembles (GGEs) characterized by the expectation values of integrals of motion. We study the dynamics of exactly solvable bosonic systems in the thermodynamic limit, ... More
Impact of the $b \to s ll$ anomalies on dark matter physicsJun 14 2017Nov 01 2017Recently, the LHCb collaboration has reported the excesses in the $b \to s ll$ processes. One of the promising candidates for new physics to explain the anomalies is the extended Standard Model (SM) with vector-like quarks and leptons. In that model, ... More
Efficient algorithm to select tuning parameters in sparse regression modeling with regularizationSep 12 2011Jan 04 2012In sparse regression modeling via regularization such as the lasso, it is important to select appropriate values of tuning parameters including regularization parameters. The choice of tuning parameters can be viewed as a model selection and evaluation ... More
Fractional operators on weighted Morrey spacesDec 02 2016A necessary condition and a sufficient condition for one weight norm inequalities on Morrey spaces to hold are given for the fractional maximal operator and the fractional integral operator. We clarify the difference between the behavior of the fractional ... More
Dust formation and mass loss around intermediate-mass AGB stars wi th initial metallicity $Z_{\rm ini} \leq 10^{-4}$ in the early Universe I: Effect of surface opacity on the stellar evolution and dust-driven windDec 06 2016Dust formation and resulting mass loss around Asymptotic Giant Branch (AGB) stars with initial metallicity in the range of $0 \leq Z_{\rm ini} \leq 10^{-4}$ and initial mass $2\leq M_{\rm ini}/M_{\odot} \leq 5$ are explored by the hydrodynamical calculations ... More
Relic Abundance in Secluded Dark Matter Scenario with Massive MediatorJul 28 2016Nov 02 2016The relic abundance of the dark matter (DM) particle $d$ is studied in a secluded DM scenario, in which the $d$ number decreasing process dominantly occurs not through the pair annihilation of $d$ into the standard model particles, but via the $dd \to ... More
Riddled-like Basin in Two-Dimensional Map for Bouncing Motion of an Inelastic Particle on a Vibrating BoardJun 07 2002Motivated by bouncing motion of an inelastic particle on a vibrating board, a simple two-dimensional map is constructed and its behavior is studied numerically. In addition to the typical route to chaos through a periodic doubling bifurcation, we found ... More
Tunneling properties of Bogoliubov mode and spin wave modes in supercurrent states of a spin-1 ferromagnetic spinor Bose-Einstein condensateFeb 15 2011We investigate tunneling properties of collective excitations in the ferromagnetic phase of a spin-1 spinor Bose-Einstein condensate (BEC). In addition to the Bogoliubov mode, this superfluid phase has two spin excitations, namely, the gapless transverse ... More
Zero and First Sound in Normal Fermi SystemsOct 17 2009On the basis of a moment method, general solutions of a linearized Boltzmann equation for a normal Fermi system are investigated. In particular, we study the sound velocities and damping rates as functions of the temperature and the coupling constant. ... More
Impact of anisotropic stress of free-streaming particles on gravitational waves induced by cosmological density perturbationsDec 02 2014Jan 08 2015Gravitational waves (GWs) are inevitably induced at second-order in cosmological perturbations through non-linear couplings with first order scalar perturbations, whose existence is well established by recent cosmological observations. So far, the evolution ... More
Error Asymmetry in Causal and Anticausal RegressionOct 11 2016It is generally difficult to make any statements about the expected prediction error in an univariate setting without further knowledge about how the data were generated. Recent work showed that knowledge about the real underlying causal structure of ... More
Modular symmetry in magnetized/intersecting D-brane modelsAug 22 2016We study the modular symmetry in four-dimensional low-energy effective field theory, which is derived from type IIB magnetized D-brane models and type IIA intersecting D-brane models. We analyze modular symmetric behaviors of perturbative terms and non-perturbative ... More
Standard Model-like D-brane models and gauge couplingsSep 09 2014Jul 31 2015We systematically search intersecting D-brane models, which just realize the Standard Model chiral matter contents and gauge symmetry. We construct new classes of non-supersymmetric Standard Model-like models. We also study gauge coupling constants of ... More
Basin structure in the two-dimensional dissipative circle mapSep 03 2003Fractal basin structure in the two-dimensional dissipative circle map is examined in detail. Numerically obtained basin appears to be riddling in the parameter region where two periodic orbits co-exist near a boundary crisis, but it is shown to consist ... More
Computing p-values of LiNGAM outputs via Multiscale BootstrapSep 16 2009Jun 22 2010Structural equation models and Bayesian networks have been widely used to study causal relationships between continuous variables. Recently, a non-Gaussian method called LiNGAM was proposed to discover such causal models and has been extended in various ... More
Excitation Transport through a Domain Wall in a Bose-Einstein CondensateAug 02 2012We investigate the tunneling properties of collective excitations through a domain wall in the ferromagnetic phase of a spin-1 spinor Bose--Einstein condensate. Within the mean-field theory at T=0, we show that the transverse spin wave undergoes perfect ... More
Weak lensing induced by second-order vector modeMay 11 2015Oct 07 2015The vector mode of cosmological perturbation theory imprints characteristic signals on the weak lensing signals such as curl- and B-modes which are never imprinted by the scalar mode. However, the vector mode is neglected in the standard first-order cosmological ... More
Generalized Morrey spaces and trace operatorMay 27 2016The theory of generalized Besov-Morrey spaces and generalized Triebel-Lizorkin-Morrey spaces is developed. Generalized Morrey spaces, which T. Mizuhara and E. Nakai proposed, are equipped with a parameter and a function. The trace property is one of the ... More
Majorana neutrino mass structure induced by rigid instatons on toroidal orbifoldNov 30 2015We study effects of D-brane instantons wrapping rigid cycles on Z2*Z2' toroidal orbifold. We compute Majorana masses induced by rigid D-brane instantons and realize bimaximal mixing matrices in certain models. We can also derive more generic mass matrices ... More
CMB power spectra induced by primordial cross-bispectra between metric perturbations and vector fieldsSep 15 2012Dec 17 2012We study temperature and polarization anisotropies of the cosmic microwave background (CMB) radiation sourced from primordial cross-bispectra between metric perturbations and vector fields, which are generated from the inflation model where an inflaton ... More
A Bayesian estimation approach to analyze non-Gaussian data-generating processes with latent classesAug 02 2014A large amount of observational data has been accumulated in various fields in recent times, and there is a growing need to estimate the generating processes of these data. A linear non-Gaussian acyclic model (LiNGAM) based on the non-Gaussianity of external ... More
Anomalous tunneling of collective excitations and effects of superflow in the polar phase of a spin-1 spinor Bose-Einstein condensateMay 14 2011We investigate tunneling properties of collective modes in the polar phase of a spin-1 spinor Bose-Einstein condensate. This spinor BEC state has two kinds of gapless modes, i.e., Bogoliubov mode and spin-wave. Within the framework of the mean-field theory ... More
Magnetic field spectrum at cosmological recombination revisitedApr 15 2015Jun 03 2015If vector type perturbations are present in the primordial plasma before recombination, the generation of magnetic fields is known to be inevitable through the Harrison mechanism. In the context of the standard cosmological perturbation theory, non-linear ... More
A Realistic Extension of Gauge-Mediated SUSY-Breaking Model with Superconformal Hidden SectorOct 25 2008Feb 06 2009The sequestering of supersymmetry (SUSY) breaking parameters, which is induced by superconformal hidden sector, is one of the solutions for the mu/B_mu problem in gauge-mediated SUSY-breaking scenario. However, it is found that the minimal messenger model ... More
ParceLiNGAM: A causal ordering method robust against latent confoundersMar 29 2013Jul 29 2013We consider learning a causal ordering of variables in a linear non-Gaussian acyclic model called LiNGAM. Several existing methods have been shown to consistently estimate a causal ordering assuming that all the model assumptions are correct. But, the ... More
CMB Constraints on Stochastic Gravitational-Wave Background at Mpc scalesApr 03 2019We present robust constraints on the stochastic gravitational waves (GWs) at Mpc scales from the CMB data. CMB constraints on GWs are usually characterized as the tensor-to-scalar ratio, assuming specifically a power-law form of the primordial spectrum, ... More
Reevaluation of Higgs-Mediated mu-e Transition in the MSSMMay 20 2010Sep 10 2010We discuss the $\mu$-$e$ transition processes induced by non-holomorphic Yukawa interactions in the minimal supersymmetric standard model (MSSM). When supersymmetry is broken, the coupling structures between Higgs doublets and leptons are modified and ... More
Maximum efficiencies and performance limiting factors of inorganic and hybrid perovskite solar cellsApr 12 2019The Shockley and Queisser limit, a well-known efficiency limit for a solar cell, is based on unrealistic physical assumptions and its maximum limit is seriously overestimated. To understand the power loss mechanisms of record-efficiency cells, a more ... More
Mott Transitions and Staggered Orders in the Three-component Fermionic System: Variational Cluster ApproachMay 21 2016The variational cluster approximation is used to study the ground-state properties and single-particle spectra of the three-component fermionic Hubbard model defined on the two-dimensional square lattice at half filling. First, we show that either a paired ... More
GroupLiNGAM: Linear non-Gaussian acyclic models for sets of variablesJun 24 2010Finding the structure of a graphical model has been received much attention in many fields. Recently, it is reported that the non-Gaussianity of data enables us to identify the structure of a directed acyclic graph without any prior knowledge on the structure. ... More
WIMP dark matter in gauge-mediated SUSY breaking models and its phenomenologyMar 18 2010Jun 10 2010We propose an extended version of the gauge-mediated SUSY breaking models where extra $SU(2)_L$ doublets and singlet field are introduced. These fields are assumed to be parity-odd under an additional matter parity. In this model, the lightest parity-odd ... More
Estimation of causal orders in a linear non-Gaussian acyclic model: a method robust against latent confoundersApr 09 2012We consider to learn a causal ordering of variables in a linear non-Gaussian acyclic model called LiNGAM. Several existing methods have been shown to consistently estimate a causal ordering assuming that all the model assumptions are correct. But, the ... More
Dark matter physics, flavor physics and LHC constraints in the dark matter model with a bottom partnerDec 06 2016In the scenario that a dark matter (DM) is a weakly interacting massive particle, there are many possibilities of the interactions with the Standard Model (SM) particles to achieve the relic density of DM. In this paper, we consider one simple DM model ... More
Finding Exogenous Variables in Data with Many More Variables than ObservationsApr 06 2009Apr 07 2011Many statistical methods have been proposed to estimate causal models in classical situations with fewer variables than observations (p<n, p: the number of variables and n: the number of observations). However, modern datasets including gene expression ... More
Hierarchical Video Generation from Orthogonal Information: Optical Flow and TextureNov 27 2017Dec 01 2017Learning to represent and generate videos from unlabeled data is a very challenging problem. To generate realistic videos, it is important not only to ensure that the appearance of each frame is real, but also to ensure the plausibility of a video motion ... More
Upperbound on Squark Masses in Gauge-Mediation Model with Light GravitinoApr 18 2008We examine stabilities of our supersymmetry-breaking false vacuum in a low-energy direct gauge mediation model of SUSY breaking. The stability required in the high-temperature early universe leads to upperbounds on masses of squarks and gluino as m_\tilde{q} ... More
On the Strichartz estimates for orthonormal systems of initial data with regularityAug 18 2017The classical Strichartz estimates for the free Schr\"odinger propagator have recently been substantially generalised to estimates of the form \[ \bigg\|\sum_j\lambda_j|e^{it\Delta}f_j|^2\bigg\|_{L^p_tL^q_x}\lesssim\|\lambda\|_{\ell^\alpha} \] for orthonormal ... More
Conditions for Boundedness into Hardy spacesFeb 08 2017We obtain boundedness from a product of Lebesgue or Hardy spaces into Hardy spaces under suitable cancellation conditions for a large class of multilinear operators that includes the Coifman-Meyer class, sums of products of linear Calderon-Zygmund operators ... More
Dark matter physics, flavor physics and LHC constraints in the dark matter model with a bottom partnerDec 06 2016Mar 28 2017In the scenario that a dark matter (DM) is a weakly interacting massive particle, there are many possibilities of the interactions with the Standard Model (SM) particles to achieve the relic density of DM. In this paper, we consider one simple DM model ... More
Spin texture and spin current in excitonic phases of the two-band Hubbard modelOct 22 2018Jan 16 2019Using the mean-field approximation, we study the $k$-space spin textures and local spin currents emerged in the spin-triplet excitonic insulator states of the two-band Hubbard model defined on the square and triangular lattices. We assume a noninteracting ... More
Secondary CMB temperature anisotropies from magnetic reheatingApr 19 2019Spatially fluctuating primordial magnetic fields~(PMFs) inhomogeneously reheat the Universe when they dissipate deep inside the horizon before recombination. Such an entropy production turns into the additional photon temperature perturbations, in particular, ... More
Evolution of perturbations and cosmological constraints in decaying dark matter models with arbitrary decay mass productsFeb 12 2014Jul 16 2014Decaying dark matter (DDM) is a candidate which can solve the discrepancies between predictions of the concordance $\Lambda$CDM model and observations at small scales such as the number counts of companion galaxies of the Milky Way and the density profile ... More
Optical, transport and magnetic properties of new compound CeCd3P3Apr 14 2016We have found that CeCd$_{3}$P$_{3}$ crystallizes into a hexagonal ScAl$_{3}$C$_{3}$-type structure. The optical, transport and magnetic properties of CeCd$_{3}$P$_{3}$ were investigated by measuring the diffuse reflectance, electrical resistivity and ... More
Identifiability of an Integer Modular Acyclic Additive Noise Model and its Causal Structure DiscoveryJan 22 2014The notion of causality is used in many situations dealing with uncertainty. We consider the problem whether causality can be identified given data set generated by discrete random variables rather than continuous ones. In particular, for non-binary data, ... More
Analysis of cause-effect inference by comparing regression errorsFeb 19 2018Jan 24 2019We address the problem of inferring the causal direction between two variables by comparing the least-squares errors of the predictions in both possible directions. Under the assumption of an independence between the function relating cause and effect, ... More
Kähler moduli stabilization in semi-realistic magnetized orbifold modelsMar 09 2017We study K\"ahler moduli stabilizations in semi-realistic magnetized D-brane models based on $ Z_2\times Z_2'$ toroidal orbifolds. In type IIB compactifications, 3-form fluxes can stabilize the dilaton and complex structure moduli fields, but there remain ... More
Formulation and constraints on decaying dark matter with finite mass daughter particlesJun 10 2011Oct 03 2011Decaying dark matter cosmological models have been proposed to remedy the overproduction problem at small scales in the standard cold dark matter paradigm. We consider a decaying dark matter model in which one CDM mother particle decays into two daughter ... More
Excitonic Insulator State of the Extended Falicov-Kimball Model in the Cluster Dynamical Impurity ApproximationMay 25 2017We comparatively study the excitonic insulator state in the extended Falicov-Kimball model (EFKM, a spinless two-band model) on the two-dimensional square lattice using the variational cluster approximation (VCA) and the cluster dynamical impurity approximation ... More
Unitarity sum rules, three site moose model, and the ATLAS 2 TeV diboson anomaliesJul 05 2015Aug 25 2015We investigate $W'$ interpretations for the ATLAS 2 TeV diboson anomalies. The roles of the unitarity sum rules, which ensure the perturbativity of the longitudinal vector boson scattering amplitudes, are emphasized. We find the unitarity sum rules and ... More