Results for "Takashi Toma"

total 3541took 0.42s
Lepton Flavor Violation in the Scotogenic ModelDec 10 2013Jan 28 2014We investigate lepton flavor violation in the scotogenic model proposed by Ma in which neutrinos acquire non-zero masses at the 1-loop level. Although some works exist in this direction, they have mainly focused on the radiative decay $\ell_\alpha \to ... More
Non-thermal Production of Minimal Dark Matter via Right-handed Neutrino DecayJul 06 2015Sep 29 2015Minimal Dark Matter (MDM) stands as one of the simplest dark matter scenarios. In MDM models, annihilation and co-annihilation processes among the members of the MDM multiplet are usually very efficient, pushing the dark matter mass above $\mathcal{O}(10)$ ... More
Radiative Lepton Model and Dark Matter with Global $U(1)'$ SymmetryJan 27 2014Mar 12 2014We propose a radiative lepton model, in which the charged lepton masses are generated at one-loop level, and the neutrino masses are induced at two-loop level. On the other hand, tau mass is derived at tree level since it is too heavy to generate radiatively. ... More
A new mechanism of sterile neutrino dark matter productionFeb 08 2018We consider a scenario where the dark matter candidate is a sterile neutrino with sizable self-interactions, described by a dimension-six operator, and with negligible interactions with the Standard Model. The relic abundance is set by the freeze-out ... More
Sharp Gamma-ray Spectral Features from Scalar Dark Matter AnnihilationsMay 27 2014The search for sharp features in the gamma-ray spectrum is a promising approach to identify a signal from dark matter annihilations over the astrophysical backgrounds. In this paper we investigate the generation of gamma-ray lines and internal bremsstrahlung ... More
Evading Direct Dark Matter Detection in Higgs Portal ModelsNov 29 2016Many models of Higgs portal Dark Matter (DM) find themselves under pressure from increasingly tight direct detection constraints. In the framework of gauge field DM, we study how such bounds can be relaxed while retaining the thermal WIMP paradigm. When ... More
Can A Higgs Portal Dark Matter be Compatible with the Anti-proton Cosmic-ray?Mar 14 2012Jun 05 2012Recent direct detection experiments of Dark Matter (DM), CoGeNT and DAMA implicate a light DM of a few GeV. Such a light DM would generate a large amount of anti-proton since suppression for anti-proton flux from DM annihilation is ineffective. We discuss ... More
Observing Higgs boson production through its decay into gamma-rays: A messenger for Dark Matter candidatesNov 12 2012May 24 2013In this Letter, we study the gamma-ray signatures subsequent to the production of a Higgs boson in space by dark matter annihilations. We investigate the cases where the Higgs boson is produced at rest or slightly boosted and show that such configurations ... More
Multicomponent Dark Matter from Gauge SymmetryNov 01 2016Nov 11 2016The composition of Dark Matter (DM) remains an important open question. The current data do not distinguish between single- and multi-component DM, while in theory constructions it is often assumed that DM is composed of a single field. In this work, ... More
X-ray lines and self-interacting dark matterJun 05 2015Dec 03 2015We study the correlation between a monochromatic signal from annihilating dark matter and its self-interacting cross section. We apply our argument to a complex scalar dark sector, where the pseudo-scalar plays the role of a warm dark matter candidate ... More
3.55 keV X-ray Line Signal from Excited Dark Matter in Radiative Neutrino ModelApr 18 2014Sep 03 2014We study an exciting dark matter scenario in a radiative neutrino model to explain the X-ray line signal at $3.55$ keV recently reported by XMN-Newton X-ray observatory using data of various galaxy clusters and Andromeda galaxy. We show that the required ... More
Implications of Two-component Dark Matter Induced by Forbidden Channels and Thermal Freeze-outNov 21 2016We consider a model of two-component dark matter based on a hidden $U(1)_D$ symmetry, in which relic densities of the dark matter are determined by forbidden channels and thermal freeze-out. The hidden $U(1)_D$ symmetry is spontaneously broken to a residual ... More
Impact of Semi-annihilation of Z3 Symmetric Dark Matter with Radiative Neutrino MassesMay 22 2014Sep 09 2014We investigate a Z3 symmetric model with two-loop radiative neutrino masses. Dark matter in the model is either a Dirac fermion or a complex scalar as a result of an unbroken Z3 symmetry. In addition to standard annihilation processes, semi-annihilation ... More
Electron electric dipole moment in Inverse Seesaw modelsMay 24 2016Aug 01 2016We consider the contribution of sterile neutrinos to the electric dipole moment of charged leptons in the most minimal realisation of the Inverse Seesaw mechanism, in which the Standard Model is extended by two right-handed neutrinos and two sterile fermion ... More
Effect of Degenerate Particles on Internal Bremsstrahlung of Majorana Dark MatterNov 18 2014Sep 21 2015Gamma-rays induced by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-rays generated by internal bremsstrahlung of Majorana and real scalar dark matter is promising since it can be a leading emission of sharp ... More
Fermionic Dark Matter in Radiative Inverse Seesaw Model with U(1)_{B-L}Jul 04 2012Aug 09 2012We construct a radiative inverse seesaw model with local B-L symmetry, and investigate the flavor structure of the lepton sector and the fermionic Dark Matter. Neutrino masses are radiatively generated through a kind of inverse seesaw framework. The PMNS ... More
Electric Dipole Moments of Charged Leptons with Sterile FermionsNov 10 2015Mar 04 2016We address the impact of sterile fermions on charged lepton electric dipole moments. Any experimental signal of these observables calls for scenarios of physics beyond the Standard Model providing new sources of CP violation. In this work, we consider ... More
Electric dipole moments of charged leptons with sterile fermionsNov 10 2016We address the impact of sterile fermions on charged lepton electric dipole moments. We show that in order to have a non-vanishing contribution to electric dipole moments, the minimal extension necessitates the addition of at least two sterile fermion ... More
Reconciliation of CDM abundance and $μ\to eγ$ in a radiative seesaw modelMar 02 2009May 08 2009We reexamine relic abundance of a singlet fermion as a CDM candidate, which contributes to the neutrino mass generation through radiative seesaw mechanism. We search solutions for Yukawa couplings and the mass spectrum of relevant fields to explain neutrino ... More
Multicomponent dark matter particles in a two-loop neutrino modelMar 29 2013Jul 08 2013We construct a loop induced seesaw model in a TeV scale theory with gauged U(1)_{B-L} symmetry. Light neutrino masses are generated at two-loop level and right-handed neutrinos also obtain their masses by one-loop effect. Multi-component Dark Matters ... More
Systematic U(1)_{B-L} Extensions of Loop-Induced Neutrino Mass Models with Dark MatterApr 27 2016We study the gauged U(1)_{B-L} extensions of the models for neutrino masses and dark matter. In this class of models, tiny neutrino masses are radiatively induced through the loop diagrams, while the origin of the dark matter stability is guaranteed by ... More
New Interpretation of the Recent Result of AMS-02 and Multi-component Decaying Dark Matters with non-Abelian Discrete Flavor SymmetryApr 09 2013Dec 23 2013Recently the AMS-02 experiment has released the data of positron fraction with much small statistical error. Because of the small error, it is no longer easy to fit the data with a single dark matter for a fixed diffusion model and dark matter profile. ... More
Direct and Indirect Detection of Dark Matter in D6 Flavor Symmetric ModelApr 03 2011Jun 12 2011We study a fermionic dark matter in a non-supersymmetric extension of the standard model with a family symmetry based on D6xZ2xZ2. In our model, the final state of the dark matter annihilation is determined to be e+ e- by the flavor symmetry, which is ... More
Direct Detection of Leptophilic Dark Matter in a Model with Radiative Neutrino MassesJan 04 2012Mar 17 2012We consider an electro-weak scale model for Dark Matter (DM) and radiative neutrino mass generation. Despite the leptophilic nature of DM with no direct couplings to quarks and gluons, scattering with nuclei is induced at the 1-loop level through photon ... More
Enhancement of the annihilation of dark matter in a radiative seesaw modelFeb 17 2010Jul 27 2010The radiative seesaw model with an inert doublet has been shown to be attractive from a viewpoint of both neutrino masses and cold dark matter. However, if we apply this model to the explanation of the positron excess in the cosmic ray observed by PAMELA, ... More
Inert Extension of the Zee-Babu ModelAug 05 2014We propose a two-loop induced Zee-Babu type neutrino mass model at the TeV scale. Although there is no dark matter candidate in the original Zee-Babu model, that is contained in our model by introducing an unbroken discrete $Z_2$ symmetry. The discrepancy ... More
Seesaw Mechanism Confronting PAMELA in S_4 Flavor Symmetric Extra U(1) ModelOct 24 2010We study cosmic-ray anomaly observed by PAMELA based on E_6 inspired extra U(1) model with S_4 flavor symmetry. In our model, the lightest flavon has very long lifetime of O(10^18) second which is longer than the age of the universe, but not long enough ... More
Systematic U(1)_{B-L} Extensions of Loop-Induced Neutrino Mass Models with Dark MatterApr 27 2016Oct 19 2016We study the gauged U(1)_{B-L} extensions of the models for neutrino masses and dark matter. In this class of models, tiny neutrino masses are radiatively induced through the loop diagrams, while the origin of the dark matter stability is guaranteed by ... More
Neutrino masses and $μ$ terms in a supersymmetric extra U(1) modelOct 16 2009Aug 30 2010We propose a supersymmetric extra U(1) model, which can generate small neutrino masses and necessary $\mu$ terms, simultaneously. Fields including quarks and leptons are embedded in three ${\bf 27}$s of $E_6$ in a different way among generations. The ... More
Signals of dark matter in a supersymmetric two dark matter modelDec 17 2010Jun 16 2011Supersymmetric radiative neutrino mass models have often two dark matter candidates. One is the usual lightest neutralino with odd R parity and the other is a new neutral particle whose stability is guaranteed by a discrete symmetry that forbids tree-level ... More
Two Component Dark Matters in S_4 x Z_2 Flavor Symmetric Extra U(1) ModelJun 23 2011Sep 30 2011We study cosmic-ray anomaly observed by PAMELA based on E_6 inspired extra U(1) model with S_4 x Z_2 flavor symmetry. In our model, the lightest flavon has very long lifetime of O(10^{18)) second which is longer than the age of the universe, but not long ... More
Light Dark Matter Candidate in B-L Gauged Radiative Inverse SeesawOct 08 2012Mar 19 2013We study a radiative inverse seesaw model with local B-L symmetry, in which we extend the neutrino mass structure that is generated through a kind of inverse seesaw framework to the more generic one than our previous work. We focus on a real part of bosonic ... More
Two Loop Neutrino Model and Dark Matter Particles with Global $B-L$ SymmetryDec 13 2013May 25 2014We study a two loop induced seesaw model with global $U(1)_{B-L}$ symmetry, in which we consider two component dark matter particles. The dark matter properties are investigated together with some phenomenological constraints such as electroweak precision ... More
A Possible Origin of Bimodal Distribution of Gamma-Ray BurstsJul 01 2004Jan 16 2005We study the distribution of the durations of gamma-ray bursts (GRBs) in the unified model of short and long GRBs recently proposed by Yamazaki, Ioka, and Nakamura. Monte Carlo simulations show clear bimodal distributions, with lognormal-like shapes for ... More
A light Scalar Dark Matter for CoGeNT and DAMA in D_6 Flavor Symmetric ModelSep 13 2011We try to interpret a very light dark matter with mass of 5~10 GeV which is in favor of the recent experiments reported by CoGeNT and DAMA, in a non-supersymmetric extension of radiative seesaw model with a family symmetry D_6 x Z_2 x Z_2. We show that ... More
Nonthermal dark matter models and signalsNov 03 2015Mar 04 2016Many experiments exploring weakly interacting massive particles (WIMPs) such as direct, indirect and collider searches have been carried out until now. However, a clear signal of a WIMP has not been found yet and it makes us to suspect that WIMPs are ... More
Right-handed Sneutrino Dark Matter in Supersymmetric B-L ModelFeb 21 2011Jun 22 2011We show that the lightest right-handed sneutrino in TeV scale supersymmetric B-L model with inverse seesaw mechanism is a viable candidate for cold dark matter. We find that it accounts for the observed dark matter relic abundance in a wide range of parameter ... More
Probing the Efficiency of Electron-Proton Coupling in Relativistic Collisionless Shocks through the Radio Polarimetry of Gamma-Ray Burst AfterglowsSep 21 2007Dec 18 2007The late-time optical/radio afterglows of $\gamma$-ray bursts (GRBs) are believed to be synchrotron emission of electrons accelerated in relativistic collisionless shocks propagating in the ambient medium of the sources. However, the fraction $f$ of electrons ... More
Ep-Eiso Correlation in a Multiple Subjet Model of Gamma-Ray BurstsApr 28 2005Aug 22 2005We perform Monte Carlo simulations to study Ep-Eiso correlation in the context of a multiple subjet model (or inhomogeneous jet model) for gamma-ray bursts (GRBs), X-ray--rich GRBs (XRRs), and X-ray flashes (XRFs). For a single subjet, we find that Ep ... More
A Note on Supersymmetric Godel Black Holes, Strings and Rings of Minimal d=5 SupergravityOct 26 2004Nov 03 2004We show how any asymptotically flat supersymmetric solution of minimal d=5 supergravity with flat base space can be deformed into another supersymmetric asymptotically-Godel solution and apply this procedure to the recently found supersymmetric black-ring ... More
The supersymmetric solutions and extensions of ungauged matter-coupled N=1,d=4 supergravityFeb 13 2008Mar 05 2008We find the most general supersymmetric solutions of ungauged N=1,d=4 supergravity coupled to an arbitrary number of vector and chiral supermultiplets, which turn out to be essentially pp-waves and strings. We also introduce magnetic 1-forms and their ... More
Supersymmetry and the Supergravity LandscapeJan 01 2006In the recent times a lot of effort has been devoted to improve our knowledge about the space of string theory vacua (``the landscape'') to find statistical grounds to justify how and why the theory selects its vacuum. Particularly interesting are those ... More
Non-Supersymmetric (but) Extreme Black Holes, Scalar Hair and Other Open ProblemsMay 14 1997We give a brief overview of black-hole solutions in four-dimensional supergravity theories and their extremal and supersymmetric limits. We also address problems like cosmic censorship and no-hair theorems in supergravity theories. While supergravity ... More
Another Proof of a Lemma by L. SheppNov 20 2014We give a new proof of a lemma by L. Shepp, that was used in connection to random coverings of a circle.
A Simple Derivation of Supersymmetric Extremal Black Hole AttractorsMar 14 2011Mar 16 2011We present a simple and yet rigorous derivation of the flow equations for the supersymmetric black-hole solutions of all 4-dimensional supergravities based on the recently found general form of all those solutions.
A Note on Lie-Lorentz DerivativesJun 18 2002Jun 18 2002The definition of ``Lie derivative'' of spinors with respect to Killing vectors is extended to all kinds of Lorentz tensors. This Lie-Lorentz derivative appears naturally in the commutator of two supersymmetry transformations generated by Killing spinors ... More
A Note on the D-2-Brane of the Massive Type IIA Theory and Gauged Sigma ModelsJul 11 1997Jul 31 1997Gauging the M-2-brane effective action with respect to an Abelian isometry in such a way that the invariance under gauge transformations of the 3-form potential is maintained (slightly modified) we obtain a fully covariant action with 11-dimensional target ... More
Massive and Massless Black HolesAug 08 1996We review some recent work on the existence and classification of extreme black-hole-type solutions in N=8 supergravity. For the black holes considered (those that are also solutions of N=4 supergravity and of the Einstein-Maxwell-dilaton theory with ... More
Massless Black Holes as Black Diholes and QuadruholesFeb 13 1996Apr 18 1996Massless black holes can be understood as bound states of a (positive mass) extreme a=\sqrt{3} black hole and a singular object with opposite (i.e. negative) mass with vanishing ADM (total) mass but non-vanishing gravitational field. Supersymmetric balance ... More
Absolutely continuous invariant measures for some piecewise hyperbolic affine mapsOct 31 2005A class of piecewise affine hyperbolic maps on a bounded subset of the plane is considered. It is shown that if a map from this class is sufficiently area-expanding then almost surely this map has an absolutely continuous invariant measure.
Latent Tree Language ModelJul 24 2016Sep 05 2016In this paper we introduce Latent Tree Language Model (LTLM), a novel approach to language modeling that encodes syntax and semantics of a given sentence as a tree of word roles. The learning phase iteratively updates the trees by moving nodes according ... More
The Pedestrian's Guide to Local TimeDec 30 2015These notes contains an introduction to the theory of Brownian and diffusion local time, as well as its relations to the Tanaka Formula, the extended Ito-Tanaka formula for convex functions, the running maximum process, and the theory of regulated stochastic ... More
A unified approach to determining the early exercise boundary position at expiry for American style of general class of derivativesDec 01 2010Mar 24 2011In this paper, we present a new method for calculating the limit of early exercise boundary at expiry. We price American style of general derivative using a formula expressed as a sum of the value of European style of derivative and so called American ... More
Numerical solution for the anisotropic Willmore flow of graphsNov 13 2011The Willmore flow is well known problem from the differential geometry. It minimizes the Willmore functional defined as integral of the mean-curvature square over given manifold. For the graph formulation, we derive modification of the Willmore flow with ... More
No elliptic islands for the universal area-preserving mapDec 10 2010Jun 02 2011A renormalization approach has been used in \cite{EKW1} and \cite{EKW2} to prove the existence of a \textit{universal area-preserving map}, a map with hyperbolic orbits of all binary periods. The existence of a horseshoe, with positive Hausdorff dimension, ... More
Relative commutator theory in varieties of omega-groupsMay 11 2006We introduce a new notion of commutator which depends on a choice of subvariety in any variety of omega-groups. We prove that this notion encompasses Higgins's commutator, Froehlich's central extensions and the Peiffer commutator of precrossed modules. ... More
Twenty-Five Moves Suffice for Rubik's CubeMar 24 2008How many moves does it take to solve Rubik's Cube? Positions are known that require 20 moves, and it has already been shown that there are no positions that require 27 or more moves; this is a surprisingly large gap. This paper describes a program that ... More
A note on the cone of mobile curvesAug 05 2009S. Boucksom, J.-P. Demailly, M. Paun and Th. Peternell proved that the cone of mobile curves ME(X) of a projective complex manifold X is dual to the cone generated by classes of effective divisors and conjectured an extension of this duality in the Kaehler ... More
Spontaneous symmetry breaking in the linear sigma model at finite chemical potential: One-loop correctionsJul 10 2006Sep 22 2006We investigate spontaneous symmetry breaking within the linear sigma model with the SU(2)xU(1) internal symmetry at finite chemical potential, which was suggested as a model for kaon condensation in the CFL phase of dense quark matter. One-loop corrections ... More
Bounded sets of sheaves on compact Kaehler manifoldsMar 30 2011Jun 02 2011We show that any set of quotients with fixed Chern classes of a given coherent sheaf on a compact Kaehler manifold is bounded in a sense which we define. The result is proved by adapting Grothendieck's boundedness criterium expressed via the Hilbert polynomial ... More
A new approach to Sobolev spaces in metric measure spacesApr 29 2015Apr 19 2016Let $(X,d_X,\mu)$ be a metric measure space where $X$ is locally compact and separable and $\mu$ is a Borel regular measure such that $0 <\mu(B(x,r)) <\infty$ for every ball $B(x,r)$ with center $x \in X$ and radius $r>0$. We define $\mathcal{X}$ to be ... More
A Note on Random Coverings of ToriJul 04 2013Apr 07 2014This note provides a generalisation of a recent result by J\"arvenp\"a\"a, J\"arvenp\"a\"a, Koivusalo, Li, and Suomala, (to appear), on the dimension of limsup-sets of random coverings of tori. The result in this note is stronger in the sense that it ... More
Random iterated function systems with smooth invariant densitiesMar 17 2009We consider some random iterated function systems on the interval and show that the invariant measure has density in $\mathcal{C}^\infty$. To prove this we use some techniques for contractions in cone metrics, applied to the transfer operator.
A Unified Model for Gamma-Ray BurstsFeb 23 2005A possible unified model of short and long gamma-ray bursts (GRBs), X-ray rich GRBs, and X-ray flashes is proposed. It is assumed that the jet of a GRB consists of many emitting sub-shells (i.e., an inhomogeneous jet model). The multiplicity of the sub-shells ... More
A Unified Model of Short and Long Gamma-Ray Bursts, X-Ray Rich Gamma-Ray Bursts, and X-Ray FlashesOct 29 2004We propose a possible unified model of short and long gamma-ray bursts (GRBs), X-ray rich GRBs, and X-ray flashes. The jet of a GRB is assumed to consist of multiple sub-jets or sub-shells (i.e., an inhomogeneous jet model). The multiplicity of the sub-jets ... More
Efficiency Crisis of Swift Gamma-Ray Bursts with Shallow X-ray Afterglows: Prior Activity or Time-Dependent Microphysics?Nov 27 2005Jul 27 2006Most X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase t^{-1/2} in the first few hours. This is not predicted by the standard afterglow model and needs an explanation. We discuss that the shallow decay ... More
Two Loop Neutrino Model with Dark Matter and LeptogenesisMay 18 2015Jul 08 2016We study a two-loop induced radiative neutrino model at TeV scale with global $U(1)$ symmetry, in which we analyze dark matter and resonant leptogenesis. The model includes two kinds of dark matter candidates. We discuss what kind of dark matter can satisfy ... More
A Model of Neutrino Mass and Dark Matter with an Accidental SymmetryApr 22 2015Nov 08 2015We present a model of radiative neutrino mass that automatically contains an accidental $Z_2$ symmetry and thus provides a stable dark matter candidate. This allows a common framework for the origin of neutrino mass and dark matter without invoking any ... More
Low-Luminosity GRB 060218: A Collapsar Jet from a Neutron Star, Leaving a Magnetar as a Remnant?Oct 30 2006Jan 08 2007The gamma-ray burst (GRB) 060218 has ~ 10^5 times lower luminosity than typical long GRBs, and is associated with a supernova (SN). The radio afterglow displays no jet break, so that this burst might arise from a mildly-relativistic spherical outflow ... More
Unstable GRB photospheres and electron-positron annihilation linesAug 09 2007We propose an emission mechanism of prompt gamma-ray bursts (GRBs) that can reproduce the observed non-thermal spectra with high radiative efficiencies, >50%. Internal dissipation below a photosphere can create a radiation-dominated thermal fireball. ... More
Tail Emission of Prompt Gamma-Ray Burst JetsSep 07 2005Apr 04 2006Tail emission of the prompt gamma-ray burst (GRB) is discussed using a multiple emitting sub-shell (inhomogeneous jet, sub-jets or mini-jets) model, where the whole GRB jet consists of many emitting sub-shells. One may expect that such a jet with angular ... More
Shallow Decay of Early X-ray Afterglows from Inhomogeneous Gamma-Ray Burst JetsNov 25 2005Feb 16 2006Almost all the X-ray afterglows of gamma-ray bursts (GRBs) observed by the Swift satellite have a shallow decay phase in the first thousands of seconds. We show that in an inhomogeneous jet (multiple-subjet or patchy-shell) model the superposition of ... More
Water Observed in Red Giant and Supergiant Stars - Manifestation of a Novel Picture of the Stellar Atmosphere or else Evidence against the Classical Model Stellar PhotosphereSep 24 2002We detected the H2O 6.3 micron bands in more than 30 normal red giants stars from K5III to M8III as well as in some early M supergiants on the SWS spectra retrieved from the ISO Data Archive. This result, however, shows serious inconsistency with the ... More
Dust in the Photospheric Environment: Unified Cloudy Models of M, L, and T DwarfsApr 24 2002May 02 2002We address the problem of how dust forms and how it could be sustained in the static photospheres of cool dwarfs for a long time. In the cool and dense gas, dust forms easily at the condensation temperature, T_cond, and the dust can be in detailed balance ... More
A Bratteli--Vershik representation for all zero-dimensional systemsMar 12 2016We show that every zero-dimensional system can have Bratteli--Vershik representation. As a corollary, we get an analogue of the Krieger's Lemma for zero-dimensional systems.
High-energy effects on the spectrum of inflationary gravitational wave background in braneworld cosmologyJan 16 2006Apr 14 2006We discuss the cosmological evolution of the inflationary gravitational wave background (IGWB) in the Randall-Sundrum single-brane model. In the braneworld cosmology, in which three-dimensional space-like hypersurface that we live in is embedded in five-dimensional ... More
Simple proof of the functional relation for the Lerch type Tornheim double zeta functionDec 06 2010Dec 07 2010In this paper, we give a simple proof of the functional relation for the Lerch type Tornheim double zeta function. By using it, we obtain simple proofs of some explicit evaluation formulas for double $L$-values.
Equations associated to the Principal Congruence Subgroup of Level EightMar 22 2016The purpose of this paper is to find an equation with respect to the principal congruence subgroup of level eight without considering modular functions.
A pentaquark picture of Lambda(1405)Aug 17 2007We test a pentaquark model of the negative parity hyperon Lambda(1405). We use a model where valence four quarks and one antiquark move in a potential relativistically and interact with each other and themselves through gluon and NG boson. Fall-apart ... More
Generalized Classical BRST Cohomology and Reduction of Poisson ManifoldsJul 23 1992In this paper, we formulate a generalization of the classical BRST construction which applies to the case of the reduction of a poisson manifold by a submanifold. In the case of symplectic reduction, our procedure generalizes the usual classical BRST ... More
Compositeness of gauge boson and asymptotic freedom in non-abelian gauge theoryOct 18 2000In order to investigate the composite gauge field, we consider the compositeness condition (i.e. renormalization constant $Z_3=0$) in the general non-abelian gauge field theory. We calculate $Z_3$ at the next-to-leading order in $1/N_f$ expansion ($N_f$ ... More
Power-law exponent of the Bouchaud-Mézard model on regular random networkJul 18 2013We study the Bouchaud-M\'ezard model on a regular random network. By assuming adiabaticity and independency, and utilizing the generalized central limit theorem and the Tauberian theorem, we derive an equation that determines the exponent of the probability ... More
Almost collapse mass quantization in 2D Smoluchowski-Poisson equationNov 22 2013We study Smoluchowski-Poisson equation in two space dimensions provided with Dirichlet boundary condition for the Poisson part. For this equation several profiles of blowup solution have been noticed. Here we show collapse mass quantization with possible ... More
More on $U_q(su(1,1))$ with $q$ a Root of UnityDec 10 1993Highest weight representations of $U_q(su(1,1))$ with $q=\exp \pi i/N$ are investigated. The structures of the irreducible hieghesat weight modules are discussed in detail. The Clebsch-Gordan decomposition for the tensor product of two irreducible representations ... More
Quasi-equilibrium nonadditivityApr 30 2014The possibility that a short-range interacting system exhibits nonadditivity is investigated. After the discussion on the precise definition of additivity and its consequence, we show that it is possible when the system is in a quasi-equilibrium state ... More
Exactness of the mean-field dynamics in optical cavity systemsDec 30 2012Jun 20 2013Validity of the mean-field approach to open system dynamics in the optical cavity system is examined. It is rigorously shown that the mean-field approach is justified in the thermodynamic limit. The result is applicable to nonequilibrium situations, e.g. ... More
Microcanonical Analysis of Exactness of the Mean-Field Theory in Long-Range Interacting SystemsNov 04 2011May 23 2012Classical spin systems with nonadditive long-range interactions are studied in the microcanonical ensemble. It is expected that the entropy of such a system is identical to that of the corresponding mean-field model, which is called "exactness of the ... More
Extensive increase of entropy in quantum quenchJun 23 2016Oct 25 2016In the setup of isolated quantum systems, it is proved that the thermodynamic entropy and the diagonal entropy must increase extensively in any nontrivial quantum quench. The extensive increase of the thermodynamic entropy is shown for any initial state ... More
Dispersionless BKP Hierarchy and Quadrant Löwner EquationAug 21 2013Mar 14 2014We show that $N$-variable reduction of the dispersionless BKP hierarchy is described by a L\"owner type equation for the quadrant.
A simple proof of the generalized strong recurrence for any non-zero parameterJun 16 2010Sep 22 2010The strong recurrence is equivalent to the Riemann hypothesis. In the present paper, we give a simple proof of the generalized strong recurrence for all non-zero parameters.
The generalized strong recurrence for non-zero rational parametersJun 09 2010The strong recurrence is equivalent to the Riemann hypothesis. On the other hand, the generalized strong recurrence holds for any irrational number. In this paper, we show the generalized strong recurrence for all non-zero rational numbers. Moreover, ... More
Off-axis Emission from the Beamed Afterglow of Gamma Ray Bursts and a Possible Interpretation of Slowly Declining X-Ray Afterglow of GRB980425Jul 16 1999A formula for off-axis emissions from the beamed afterglow of GRBs in a synchrotron model is derived. The formula is applied to an inhomogeneous circumstellar matter obeying n proportional to 1/r**2 suggested for SN1998bw/GRB980425. The slow decline rate ... More
Scale-Free Networks Hidden in Chaotic Dynamical SystemsJul 22 2010In this paper, we show our discovery that state-transition networks in several chaotic dynamical systems are "scale-free networks," with a technique to understand a dynamical system as a whole, which we call the analysis for "Discretized-State Transition" ... More
Dressed Quark Propagator at Finite Temperature in the Schwinger-Dyson approach with the Rainbow Approximation - exact numerical solutions and their physical implicationJul 10 2001The Schwinger-Dyson equation for the quark in the rainbow approximation at finite temperature (T) is solved numerically without introducing any ansatz for the dressed quark propagator. The dymanical quark mass-function and the wave-function renormalization ... More
Strong field physics in condensed matterFeb 12 2011There are deep similarities between non-linear QFT studied in high-energy and non-equilibrium physics in condensed matter. Ideas such as the Schwinger mechanism and the Volkov state are deeply related to non-linear transport and photovoltaic Hall effect ... More
Fast construction of higher order digital nets for numerical integration in weighted Sobolev spacesMay 07 2013Aug 07 2014Higher order digital nets are special classes of point sets for quasi-Monte Carlo rules which achieve the optimal convergence rate for numerical integration of smooth functions. An explicit construction of higher order digital nets was proposed by Dick, ... More
Constructing good higher order polynomial lattice rules with modulus of reduced degreeOct 21 2013Oct 01 2014In this paper we investigate multivariate integration in weighted unanchored Sobolev spaces of smoothness of arbitrarily high order. As quadrature points we employ higher order polynomial lattice point sets over $\mathbb{F}_{2}$ which are randomly digitally ... More
Finite rank Bratteli--Vershik homeomorphisms are expansiveJun 01 2016Aug 19 2016Downarowicz and Maass (2008) have shown that every Cantor minimal homeomorphism with finite topological rank $K > 1$ is expansive. Bezuglyi, Kwiatkowski, and Medynets (2009) extended the result to non-minimal aperiodic cases. In this paper, we show that ... More
Propagation of the surface plasmon polaritons through gradient index and periodic structuresApr 01 2010We study the propagation of surface electromagnetic waves along the metallic surface covered by various layered dielectric structures. We show that strong radiative losses typical for the scattering of the surface wave can be considerably suppressed when ... More
Early exercise boundary for American type of floating strike Asian option and its numerical approximationDec 07 2009In this paper we generalize and analyze the model for pricing American-style Asian options due to (Hansen and Jorgensen 2000) by including a continuous dividend rate $q$ and a general method of averaging of the floating strike. We focus on the qualitative ... More