Results for "Hiroyuki Nakano"

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BEC polaron in harmonic trap potential at weak coupling regime: Lee-Low-Pines type approachOct 03 2016Feb 22 2017We have calculated the zero-temperature binding energy of a single impurity atom immersed in a Bose-Einstein condensate of ultracold atoms that are trapped in an axially symmetric harmonic potential, where the impurity interacts with bosonic atoms in ... More
A note on gravitational wave extraction from binary simulationsJan 13 2015Aug 20 2015In previous works, we developed a perturbative extrapolation formula to obtain gravitational waves at infinity from binary black hole simulations, based on the Regge-Wheeler-Zerilli formalism. In practice, this formula was basically derived in a background ... More
An Improved Search Method for Gravitational Ringing of Black HolesMar 16 2004A black hole has characteristic quasi-normal modes that will be excited when it is formed or when the geometry is perturbed. The state of a black hole when the quasi-normal modes are excited is called the gravitational ringing, and detections of it will ... More
Comparison of Post-Newtonian and Numerical Evolutions of Black-Hole BinariesJan 24 2009In this paper, we compare the waveforms from the post-Newtonian (PN) approach with the numerical simulations of generic black-hole binaries which have mass ratio $q\sim0.8$, arbitrarily oriented spins with magnitudes $S_1/m_1^2\sim0.6$ and $S_2/m_2^2\sim0.4$, ... More
Intermediate-mass-ratio black hole binaries: intertwining numerical and perturbative techniquesAug 25 2010Dec 02 2010We describe in detail full numerical and perturbative techniques to compute the gravitational radiation from intermediate-mass-ratio black-hole-binary inspirals and mergers. We perform a series of full numerical simulations of nonspinning black holes ... More
How close can we approach the event horizon of the Kerr black hole from the detection of the gravitational quasinormal modes?Feb 07 2016Using the WKB method, we show that the peak location ($r_{\rm peak}$) of the potential, which determines the quasinormal mode frequency of the Kerr black hole, obeys an accurate empirical relation as a function of the specific angular momentum $a$ and ... More
Gravitational waves from dark matter collapse in a starOct 04 2015Jan 14 2016We investigate the collapse of clusters of weakly interacting massive particles (WIMPs) in the core of a Sun-like star and the possible formation of mini-black holes and the emission of gravitational waves. When the number of WIMPs is small, thermal pressure ... More
Second Order Quasi-Normal Mode of the Schwarzschild Black HoleAug 03 2007We formulate and calculate the second order quasi-normal modes (QNMs) of a Schwarzschild black hole (BH). Gravitational wave (GW) from a distorted BH, so called ringdown, is well understood as QNMs in general relativity. Since QNMs from binary BH mergers ... More
Gravitational reaction force on a particle in the Schwarzschild backgroundOct 10 2000Jan 17 2001We formulate a new method to calculate the gravitational reaction force on a particle of mass $\mu$ orbiting a massive black hole of mass $M$. In this formalism, the tail part of the retarded Green function, which is responsible for the reaction force, ... More
Hybrid black-hole binary initial dataDec 04 2010Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt ... More
Inspiraling black-hole binary spacetimes: Challenges in transitioning from analytical to numerical techniquesApr 01 2015Jun 23 2016We explore how a recently developed analytical black-hole binary spacetime can be extended using numerical simulations to go beyond the slow-inspiral phase. The analytic spacetime solves the Einstein field equations approximately, with the approximation ... More
Second and higher-order quasi-normal modes in binary black hole mergersApr 26 2007Aug 03 2007Black hole (BH) oscillations known as quasi-normal modes (QNMs) are one of the most important gravitational wave (GW) sources. We propose that higher perturbative order of QNMs, generated by nonlinear gravitational interaction near the BHs, are detectable ... More
BEC-Polaron gas in a boson-fermion mixture : a many-body extension of Lee-Low-Pines theoryDec 15 2015May 18 2016We investigate the ground state properties of the gaseous mixture of a single species of bosons and fermions at zero temperature, where bosons are major in population over fermions, and form the Bose-Einstein condensate (BEC). The boson-boson and boson-fermion ... More
Three-body equations of motion in successive post-Newtonian approximationsOct 29 2007There are periodic solutions to the equal-mass three-body (and N-body) problem in Newtonian gravity. The figure-eight solution is one of them. In this paper, we discuss its solution in the first and second post-Newtonian approximations to General Relativity. ... More
Regular second order perturbations of binary black holes: The extreme mass ratio regimeApr 24 2008In order to derive the precise gravitational waveforms for extreme mass ratio inspirals (EMRI), we develop a formulation for the second order metric perturbations produced by a point particle moving in the Schwarzschild spacetime. The second order waveforms ... More
Circumbinary MHD Accretion into Inspiraling Binary Black HolesApr 04 2012As 2 black holes bound to each other in a close binary approach merger their inspiral time becomes shorter than the characteristic inflow time of surrounding orbiting matter. Using an innovative technique in which we represent the changing spacetime in ... More
Regular second order perturbations of extreme mass ratio black hole binariesJan 05 2007We report on the first results of self-consistent second order metric perturbations produced by a point particle moving in the Schwarzschild spacetime. The second order waveforms satisfy a wave equation with an effective source term build up from products ... More
A new method to integrate (2+1)-wave equations with Dirac's delta functions as sourcesFeb 28 2008Apr 21 2008Unlike in the Schwarzschild black hole background, gravitational perturbations in a Kerr black hole background can not be decomposed into simple tensor harmonics in the time domain. Here, we make mode decompositions only in the azimuthal direction. As ... More
New method to integrate 2+1 wave equations with Dirac's delta functions as sourcesJan 17 2008Gravitational perturbations in a Kerr black hole background can not be decomposed into simple tensor harmonics in the time domain. Here, we make the mode decomposition only in the azimuthal direction and discuss the resulting (2+1)-dimensional Klein-Gordon ... More
Bose-Einstein condensation and density collapse in a weakly coupled boson-fermion mixtureDec 15 2014We investigate the mechanical instability toward density collapse and the transition temperature of Bose-Einstein condensation in the weakly coupled boson-fermion many-body mixture of single-component boson and fermion gases, in the case of the repulsive ... More
Gravitational wave quasinormal mode from Population III massive black hole binaries in various models of population synthesisJun 01 2016Focusing on the remnant black holes after merging binary black holes, we show that ringdown gravitational waves of Population III binary black holes mergers can be detected with the rate of $5.9-500~{\rm events~yr^{-1}}~({\rm SFR_p}/ (10^{-2.5}~M_\odot~{\rm ... More
Possible golden events for ringdown gravitational wavesJun 01 2015Sep 03 2015There is a forbidden region in the parameter space of quasinormal modes of black holes in general relativity. Using both inspiral and ringdown phases of gravitational waves from binary black holes, we propose two methods to test general relativity. We ... More
Bose polaron in spherically symmetric trap potentials: Ground states with zero and lower angular momentaJan 09 2019Mar 28 2019Single-atomic impurities immersed in a dilute Bose gas in the spherically symmetric harmonic trap potentials are studied at zero temperature. In order to find the ground state of the polarons, we present a conditional variational method with fixed expectation ... More
Self-Force on a Scalar Charge in Circular Orbit around a Schwarzschild Black HoleApr 04 2001Apr 12 2001In an accompanying paper, we have formulated two types of regulariz_ation methods to calculate the scalar self-force on a particle of charge $q$ moving around a black hole of mass $M$, one of which is called the ``power expansion regularization''. In ... More
Covariant Self-force Regularization of a Particle Orbiting a Schwarzschild Black Hole - Mode Decomposition Regularization -Nov 21 2001Covariant structure of the self-force of a particle in a general curved background has been made clear in the cases of scalar [Quinn], electromagnetic [DeWittBrehme], and gravitational charges [QuinnWald]. Namely, what we need is the part of the self-field ... More
BEC polaron in harmonic trap potential at weak coupling regime: Lee-Low-Pines type approachOct 03 2016We have calculated the zero-temperature binding energy of a single impurity atom immersed in a Bose-Einstein condensate of ultracold atoms that are trapped in an axially symmetric harmonic potential, where the impurity interacts with bosonic atoms in ... More
The possible existence of Pop III NS-BH binary and its detectabilityOct 02 2016In the population synthesis simulations of Pop III stars, many BH (Black Hole)-BH binaries with merger time less than the age of the Universe $(\tau_{\rm H})$ are formed, while NS (Neutron Star)-BH binaries are not. The reason is that Pop III stars have ... More
The detection of quasinormal mode with $a/M \sim 0.95$ would prove a sphere $99\%$ soaking in the ergoregion of the Kerr space-timeFeb 09 2016Recent numerical relativity simulations of mergers of binary black holes suggest that the maximum final value of $a/M$ is $\sim 0.95$ for the coalescence of two equal mass black holes with aligned spins of the same magnitude $a/M=0.994$ which is close ... More
Black Strings in Our WorldMar 14 2005The brane world scenario is a new approach to resolve the problem on how to compactify the higher dimensional spacetime to our 4-dimensional world. One of the remarkable features of this scenario is the higher dimensional effects in classical gravitational ... More
Soft Supersymmetry Breaking at Heavy Chiral ThresholdDec 28 2006We discuss the structure of threshold corrections to soft supersymmetry-breaking parameters at the mass threshold of heavy chiral superfields. Nontrivial dependence on soft parameters of heavy matter fields originates from the `physical' definition of ... More
Gauge Problem in the Gravitational Self-Force I. Harmonic Gauge Approach in the Schwarzschild BackgroundAug 21 2002The metric perturbation induced by a particle in the Schwarzschild background is usually calculated in the Regge-Wheeler (RW) gauge, whereas the gravitational self-force is known to be given by the tail part of the metric perturbation in the harmonic ... More
Possible confirmation of the existence of ergoregion by the Kerr quasinormal mode in gravitational waves from Pop III massive black hole binaryJan 26 2016Feb 01 2016The existence of the ergoregion of the Kerr space-time has not been confirmed observationally yet. We show that the confirmation would be possible by observing the quasinormal mode in gravitational waves. As an example, using the recent population synthesis ... More
Self-force Regularization in the Schwarzschild SpacetimeNov 30 2004We discuss the gravitational self-force on a particle in a black hole space-time. For a point particle, the full (bare) self-force diverges. The metric perturbation induced by a particle can be divided into two parts, the direct part (or the S part) and ... More
Spin flips in generic black hole binariesJun 15 2015Jan 18 2016We study the spin dynamics of individual black holes in a binary system. In particular we focus on the polar precession of spins and the possibility of a complete flip of spins with respect to the orbital plane. We perform a full numerical simulation ... More
Comparing an analytical spacetime metric for a merging binary to a fully non-linear numerical evolution using curvature scalarsFeb 08 2018We introduce a new geometrically invariant prescription for comparing two different spacetimes based on geodesic deviation. We use this method to compare a family of recently introduced analytical spacetime representing inspiraling black-hole binaries ... More
Accuracy of the Post-Newtonian Approximation for Extreme-Mass Ratio Inspirals from Black-hole Perturbation ApproachJan 10 2016May 25 2016We revisit the accuracy of the post-Newtonian (PN) approximation and its region of validity for quasi-circular orbits of a point particle in the Kerr spacetime, by using an analytically known highest post-Newtonian order gravitational energy flux and ... More
Gauge Problem in the Gravitational Self-Force II. First Post Newtonian Force under Regge-Wheeler GaugeAug 11 2003Oct 02 2003We discuss the gravitational self-force on a particle in a black hole space-time. For a point particle, the full (bare) self-force diverges. It is known that the metric perturbation induced by a particle can be divided into two parts, the direct part ... More
The detection of Quasinormal Mode of Pop III Binary Black Hole merger with final $M \sim 60M_\odot$ and $a/M \sim 0.7$ would confirm the strong gravity space-time around $\sim 2M$ which is only $\sim 1.17$ times the event horizon radiusJan 04 2016Jan 26 2016Recent population synthesis simulations of Pop III stars suggest that the event rate of coalescence of $\sim 30M_\odot$--$30M_\odot$ binary black holes can be high enough for the detection by the second generation gravitational wave detectors. The frequencies ... More
Fluctuation of density of states for 1d Schrödinger operatorsMay 19 2016We consider the 1d Schr\"odinger operator with random decaying potential and compute the 2nd term asymptotics of the density of states, which shows substantial differences between the cases $\alpha > \frac 12$, $\alpha < \frac 12$ and $\alpha = \frac ... More
The repulsion between localization centers in the Anderson modelMar 10 2006In this note we show that, a simple combination of deep results in the theory of random Schr\"odinger operators yields a quantitative estimate of the fact that the localization centers become far apart, as corresponding energies are close together.
The adiabatic evolution of orbital parameters in the Kerr spacetimeNov 29 2005We investigate the adiabatic orbital evolution of a point particle in the Kerr spacetime due to the emission of gravitational waves. In the case that the timescale of the orbital evolution is enough smaller than the typical timescale of orbits, the evolution ... More
Evolution of the Carter constant for a resonant inspiral into a Kerr black hole: I. The scalar caseFeb 17 2013Jun 02 2013We discuss the inspiral of a small body around a Kerr black hole. When the time scale of the radiation reaction is sufficiently longer than its orbital period, the leading order orbital evolution is described only by the knowledge of the averaged evolution ... More
Intermediate Mass Ratio Black Hole Binaries: Numerical Relativity meets Perturbation TheoryJan 13 2010We study black-hole binaries in the intermediate-mass-ratio regime 0.01 < q < 0.1 with a new technique that makes use of nonlinear numerical trajectories and efficient perturbative evolutions to compute waveforms at large radii for the leading and nonleading ... More
Statistical studies of Spinning Black-Hole BinariesOct 16 2009Jan 21 2010We study the statistical distributions of the spins of generic black-hole binaries during the inspiral and merger, as well as the distributions of the remnant mass, spin, and recoil velocity. For the inspiral regime, we start with a random uniform distribution ... More
Eccentric Binary Black Holes with Spin via the Direct Integration of the Post-Newtonian Equations of MotionApr 06 2019We integrate the third and a half post-Newtonian equations of motion for a fully generic binary black hole system, allowing both for non-circular orbits, and for one or both of the black holes to spin, in any orientation. Using the second post-Newtonian ... More
Biset functors as module Mackey functors, and its relation to derivatorsJan 22 2016In this article, we will show that the category of biset functors can be regarded as a reflective monoidal subcategory of the category of Mackey functors on the 2-category of finite groupoids. This reflective subcategory is equivalent to the category ... More
Several adjoint constructions for biset functors via Mackey-functorial interpretationJun 13 2014We consider analogs of Jacobson's $F$-Burnside construction and Boltje's $(-)_+$-construction for biset functors, using Mackey-functor theoretic interpretation of biset functors.
On Calculations of Zeros of Various L-functionsNov 09 1994As we have shown several years ago [Y2], zeros of $L(s, \Delta )$ and $L^(2)(s, \Delta )$ can be calculated quite efficiently by a certain experimental method. Here $\Delta$ denotes the cusp form of weight 12 with respect to SL$(2, Z)$ and $L(s, \Delta ... More
Low Energy Investigations at Kamioka ObservatoryJan 30 2013At Kamioka Observatory many activities for low energy rare event search are ongoing. Super-Kamiokande(SK), the largest water Cherenkov neutrino detector, currently continues data taking as the fourth phase of the experiment (SK-IV). In SK-IV, we have ... More
The initial value problem for a third order dispersive equation on the two-dimensional torusApr 01 2004May 01 2004We present the necessary and sufficient condition for the $L^2$-well-posedness of the initial problem for a third order linear dispersive equation on the two dimensional torus. Birkhoff's method of asymptotic solutions is used to prove the necessity. ... More
Magnetic excitations in La-based cuprate superconductors: slave-boson mean-field analysis of the two-dimensional t-J modelOct 22 2006Motivated by recent inelastic neutron scattering experiments up to a high-energy region for La-based cuprates, we compute (q,omega) maps of the imaginary part of the dynamical magnetic susceptibility chi(q,omega) in the slave-boson mean-field approximation ... More
The limit formula for the normalized fundamental matrix of the northwest-corner truncation of Markov chains: Matrix-infinite-product form solutions of block-Hessenberg Markov chainsMar 25 2016Jun 30 2016This paper considers the normalized fundamental matrix for the northwest-corner (NW-corner) truncation of ergodic continuous-time Markov chains, technically, of their infinitesimal generators. We first present a limit formula for the normalized fundamental ... More
Subexponential tail equivalence of the queue length distributions of BMAP/GI/1 queues with and without retrialsOct 17 2013Jul 06 2014The main contribution of this paper is to prove the subexponential tail equivalence of the stationary queue length distributions in the BMAP/GI/1 queues with and without retrials. We first present a stochastic-decomposition-like result of the stationary ... More
Electroweak Sudakov corrections at 2 loop levelFeb 14 2001In processes at the energy much higher than electroweak scale, weak boson mass act as the infrared cutoff in weak boson loops and resulting Sudakov log corrections can be as large as 10%. Since electroweak theory is off-diagonally broken gauge theory, ... More
Properties of free-free, dust, and CO emissions in the starbursts of blue compact dwarf galaxiesDec 16 2012The central star-forming regions in three blue compact dwarf galaxies (He 2-10, NGC 5253, and II Zw 40) were observed in the 340 GHz (880 micron) band at 5 arcsec resolution with the Submillimetre Array (SMA). Continuum emission associated with the central ... More
Analytic expression for pull-or-jerk experimentAug 27 2014This work focuses on a theoretical analysis of a well-known inertia demonstration, which uses a weight suspended by a string with an extra string that hangs below the weight. The point in question is which string, the upper or lower, will break when pulling ... More
Persistent current in quantum torus knotsApr 23 2012I consider the quantum interference of electrons moving along knotted trajectories under external magnetic field. The induced persistent current is formulated in terms of characteristic parameters that classify the torus knot geometry. The current is ... More
An Explicit Form of the Equation of Motion of the Interface in Bicontinuous PhasesMar 28 2000The explicit form of the interface equation of motion derived assuming a minimal surface is extended to general bicontinuous interfaces that appear in the diffusion limited stage of the phase separation process of binary mixtures. The derivation is based ... More
BV Analysis of Tachyon Fluctuation around Multi-brane Solutions in Cubic String Field TheoryNov 13 2015May 03 2016We study whether the tachyon mode exists as a physical fluctuation on the 2-brane solution and on the tachyon vacuum solution in cubic open string field theory. Our analysis is based on the Batalin-Vilkovisky formalism. We first construct a set of six ... More
A special value of the spectral zeta function of the non-commutative harmonic osciallatorsJul 06 2005The non-commutative harmonic oscillator is a $2\times2$-system of harmonic oscillators with a non-trivial correlation. We write down explicitly the special value at $s=2$ of the spectral zeta function of the non-commutative harmonic oscillator in terms ... More
Fourth-order dispersive systems on the one-dimensional torusSep 20 2013Feb 05 2014We present the necessary and sufficient conditions of the well-posedness of the initial value problem for certain fourth-order linear dispersive systems on the one-dimensional torus. This system is related with a dispersive flow for closed curves into ... More
Quasinormal modes in the extreme Kerr limit and asymptotic behavior of the Sasaki-Nakamura transformationApr 28 2016Jul 28 2016The Sasaki-Nakamura transformation gives a short-ranged potential and a convergent source term for the master equation of perturbations in the Kerr space-time. In this paper, we study the asymptotic behavior of the transformation, and present a new relaxed ... More
Black hole ringdown echoes and howlsApr 24 2017Jul 24 2017Recently the possibility of detecting echoes of ringdown gravitational waves from binary black hole mergers was shown. The presence of echoes is expected if the black hole is surrounded by a mirror that reflects gravitational waves near the horizon. Here, ... More
Adiabatic Evolution of three 'Constants' of Motion for Greatly Inclined Orbits in Kerr spacetimeFeb 09 2007May 31 2007General orbits of a particle of small mass $\mu$ around a Kerr black hole of mass $M$ are characterized by three parameters: the energy, the angular momentum and the Carter constant. The time-averaged rates of change of the energy and the angular momentum ... More
An Effective Search Method for Gravitational Ringing of Black HolesJun 18 2003Oct 07 2003We develop a search method for gravitational ringing of black holes. The gravitational ringing is due to complex frequency modes called the quasi-normal modes that are excited when a black hole geometry is perturbed. The detection of it will be a direct ... More
Comparison of Numerical and Post-Newtonian Waveforms for Generic Precessing Black-Hole BinariesAug 05 2008Jan 01 2009We compare waveforms and orbital dynamics from the first long-term, fully non-linear, numerical simulations of a generic black-hole binary configuration with post-Newtonian predictions. The binary has mass ratio q~0.8 with arbitrarily oriented spins of ... More
Spinning, Precessing, Black Hole Binary Spacetime via Asymptotic MatchingAug 02 2016We briefly discuss a method to construct a global, analytic, approximate spacetime for precessing, spinning binary black holes. The spacetime construction is broken into three parts: the inner zones are the spacetimes close to each black hole, and are ... More
Inspiralling, Non-Precessing, Spinning Black Hole Binary Spacetime via Asymptotic MatchingDec 17 2015Mar 23 2016We construct a new global, fully analytic, approximate spacetime which accurately describes the dynamics of non-precessing, spinning black hole binaries during the inspiral phase of the relativistic merger process. This approximate solution of the vacuum ... More
A simultaneous generalization of mutation and recollement on a triangulated categoryDec 07 2015In this article, we introduce the notion of {\it concentric twin cotorsion pair} on a triangulated category. This notion contains the notions of $t$-structure, cluster tilting subcategory, co-$t$-structure and functorally finite rigid subcategory as examples. ... More
Partial Tambara structure on the Burnside biset functor, induced from a derivator-like system of adjoint tripletsFeb 17 2015Dec 07 2015In the previous article 'A Mackey-functor theoretic interpretation of biset functors', we have constructed the 2-category $\mathbb{S}$ of finite sets with variable finite group actions, in which bicoproducts and bipullbacks exist. As shown in it, biset ... More
Equivalence of hearts of twin cotorsion pairs on triangulated categoriesJul 26 2014Dec 07 2015In this article, we investigate the condition for the hearts of twin cotorsion pairs to be equivalent, compatibly with the associated functors. This is related to the vanishing of components of pairs through the associated functors.
Cohomology theory in 2-categoriesNov 17 2008Recently, symmetric categorical groups are used for the study of the Brauer groups of symmetric monoidal categories. As a part of these efforts, some algebraic structures of the 2-category of symmetric categorical groups $\mathrm{SCG}$ are being investigated. ... More
Error Bounds for Augmented Truncations of Discrete-Time Block-Monotone Markov Chains under Geometric Drift ConditionsMay 16 2014Jul 17 2014This paper studies the augmented truncation of discrete-time block-monotone Markov chains under geometric drift conditions. We first present a bound for the total variation distance between the stationary distributions of an original Markov chain and ... More
A sufficient condition for the subexponential asymptotics of GI/G/1-type Markov chains with queueing applicationsOct 17 2013Jun 27 2014The main contribution of this paper is to present a new sufficient condition for the subexponential asymptotics of the stationary distribution of a GI/GI/1-type Markov chain without jumps from level "infinity" to level zero. For simplicity, we call such ... More
Light-quark baryon spectroscopy within ANL-Osaka dynamical coupled-channels approachFeb 08 2016Recent results on the study of light-quark baryons with the ANL-Osaka dynamical coupled-channels (DCC) approach are presented, which contain the N* and Delta* spectroscopy via the analysis of pi N and gamma N reactions and the Lambda* and Sigma* spectroscopy ... More
Central free-free-dominated 880 $\micron$ emission in II Zw 40Jul 29 2011The central star-forming region in a blue compact dwarf galaxy, II Zw 40, was observed in the 340 GHz ($880 \micron$) band at $\sim 5$ arcsec (250 pc) resolution with the Submillimetre Array (SMA). A source associated with the central star-forming complex ... More
Off-shell dimensional reduction of 5D orbifold supergravityOct 15 2007We present a systematic way for deriving a four-dimensional (4D) effective action of the five-dimensional (5D) orbifold supergravity respecting the N=1 {\it off-shell} structure. As an illustrating example, we derive a 4D effective theory of the 5D gauged ... More
Gauged $U(1)_R$ supergravity on orbifoldOct 11 2005We discuss a gauged $U(1)_R$ supergravity on five-dimensional orbifold ($S^1/Z_2$) in which a $Z_2$-even U(1) gauge field takes part in the $U(1)_R$ gauging, and show the structure of Fayet-Iliopoulos (FI) terms allowed in such model. Some physical consequences ... More
Fayet-Iliopoulos terms in five-dimensional orbifold supergravitySep 14 2004Oct 11 2005We derive an off-shell formulation for the boundary Fayet-Iliopoulos (FI) terms in locally supersymmetric U(1) gauge theory on 5D $S^1/Z_2$ orbifold. Some physical consequences of such FI terms, e.g., the supersymmetry breaking and the generation of 5D ... More
A two-dimensional topological representation theorem for matroid polytopes of rank 4Sep 12 2018The Folkman-Lawrence topological representation theorem, which states that every (loop-free) oriented matroid of rank $r$ can be represented as a pseudosphere arrangement on the $(r-1)$-dimensional sphere $S^{r-1}$, is one of the most outstanding results ... More
A criterion of graded coherentness of tensor algebras and its application to higher dimensional Auslander-Reiten theoryOct 19 2012Even if a ring A is coherent, the polynomial ring A[X] in one variable could fail to be coherent. In this note we show that A[X] is graded coherent with the standard grading deg X=1. More generally, we give a criterion of graded coherentness of the tensor ... More
On commutative differential graded algebrasMar 18 2019In this paper we undertake a basic study on connective commutative differential graded algebras (CDGA), more precisely, piecewise Noetherian CDGA, which is a DG-counter part of commutative Noetherian algebra. We establish basic results for example, Auslaner-Buchsbaum ... More
Adiabatic radiation reaction to the orbits in Kerr SpacetimeJun 17 2005Geodesic motion of a point particle in Kerr geometry has three constants of motion, energy $E$, azimuthal angular momentum $L$, and Carter constant $Q$. Under the adiabatic approximation, radiation reaction effect is characterized by the time evolution ... More
"Flux-balance formulae" for extreme mass-ratio inspiralsSep 28 2018Jan 21 2019The "flux-balance formulae" that determine the averaged evolution of energy, azimuthal angular momentum, and Carter constant in terms of the averaged asymptotic gravitational-wave fluxes for inspirals of small bodies into Kerr black holes were first derived ... More
Extracting the cutoff frequency in the gravitational-wave spectrum of black hole-neutron star mergersSep 08 2017The location of the cutoff in the gravitational-wave spectrum of black hole-neutron star mergers is correlated strongly with the neutron-star radius for the case that the neutron star is disrupted by the black hole during the merger. However, the modulation ... More
Extracting the orbital axis from gravitational waves of precessing binary systemsMay 21 2017Feb 19 2018We present a new method for extracting the instantaneous orbital axis only from gravitational wave strains of precessing binary systems observed from a particular observer direction. This method enables us to reconstruct the co-precessing frame waveforms ... More
Stationary Rotating Strings as Relativistic Particle MechanicsMar 28 2008Jun 23 2008Stationary rotating strings can be viewed as geodesic motions in appropriate metrics on a two-dimensional space. We obtain all solutions describing stationary rotating strings in flat spacetime as an application. These rotating strings have infinite length ... More
Calculating the gravitational self force in Schwarzschild spacetimeNov 01 2001Feb 14 2002We present a practical method for calculating the local gravitational self-force (often called ``radiation-reaction force'') for a pointlike particle orbiting a Schwarzschild black hole. This is an implementation of the method of {\it mode-sum regularization}, ... More
Estimate of the radius responsible for quasinormal modes in the extreme Kerr limit and asymptotic behavior of the Sasaki-Nakamura transformationApr 28 2016Apr 26 2017The Sasaki-Nakamura transformation gives a short-ranged potential and a convergent source term for the master equation of perturbations in the Kerr space-time. In this paper, we study the asymptotic behavior of the transformation, and present a new relaxed ... More
Asymptotically Matched Spacetime Metric for Non-Precessing, Spinning Black Hole BinariesAug 31 2012We construct a closed-form, fully analytical 4-metric that approximately represents the spacetime evolution of non-precessing, spinning black hole binaries from infinite separations up to a few orbits prior to merger. We employ the technique of asymptotic ... More
Intermediate-mass-ratio black hole binaries II: Modeling Trajectories and Gravitational WaveformsAug 22 2011We revisit the scenario of small-mass-ratio (q) black-hole binaries; performing new, more accurate, simulations of mass ratios 10:1 and 100:1 for initially nonspinning black holes. We propose fitting functions for the trajectories of the two black holes ... More
Perturbative effects of spinning black holes with applications to recoil velocitiesNov 11 2010Recently, we proposed an enhancement of the Regge-Wheeler-Zerilli formalism for first-order perturbations about a Schwarzschild background that includes first-order corrections due to the background black-hole spin. Using this formalism, we investigate ... More
Shattering by turbulence as a production source of very small grainsJun 11 2010The origin of grain size distribution in the interstellar medium is one of the most fundamental problems in the interstellar physics. In the Milky Way, smaller grains are more abundant in number, but their origins are not necessarily specified and quantified. ... More
A central extension of U_q sl(2,2)^{(1)} and R-matrices with a new parameterApr 25 2003Jun 30 2003In this paper, using a quantum superalgebra associated with the universal central extension of sl(2,2)^{(1)}, we introduce new R-matrices having an extra parameter x. As x\to 0, they become those associated with the symmetric and anti-symmetric tensor ... More
Field-free, spin-current control of magnetization in non-collinear chiral antiferromagnetsOct 24 2016Non-collinear chiral antiferromagnets like Mn3Sn and Mn3Ge are known to show gigantic anomalous Hall response depending on the orientation of their inverse chiral magnetic order of Mn atoms in Kagome layers. Here we study the stability of such magnetic ... More
How far can Tarzan jump?Aug 21 2012The tree-based rope swing is a popular recreation facility, often installed in outdoor areas, giving pleasure to thrill-seekers. In the setting, one drops down from a high platform, hanging from a rope, then swings at a great speed like "Tarzan", and ... More
Constraints on Non-Holomorphic correction in N=2 superspaceFeb 22 2001May 29 2001We study quantum corrections on four derivative term of vector multiplets in ${\cal{N}}=2$ supersymmetric Yang-Mills theory. We first show splitting of quantum correction on gauge neutral hypermultiplets from U(1) vector multiplets at four derivative ... More
Sequestering in models of F-term upliftingSep 05 2008We discuss the nature of sequestering supersymmetry breaking sectors in a certain class of moduli stabilization in supergravity/string models, where a negative vacuum energy of the nonperturbative moduli potential is canceled by dynamically generated ... More
Dynamical symmetry breaking on a brane with bulk gauge theoryDec 20 2003Aug 03 2004We analyze a structure of dynamical chiral symmetry breaking in orbifold gauge theories with matter fields (fermions) on the fixed point. We find that the boundary chiral phase structure of QED and QCD on the orbifold is quite nontrivial depending on ... More
A Method For Determining Two-Dimensional Orbits In Galactic DisksAug 16 2004Jan 04 2005We propose a method for determining the two-dimensional orbits of interstellar matter (ISM) in galactic disks using observed line-of-sight velocity fields. Although four components, consisting of two of position and two of velocity, are necessary to determine ... More