Showing papers in "Progress of Theoretical Physics in 2011"
TL;DR: In this paper, the generalized Galileons were used as a framework to develop the most general single-field inflation models ever, Generalized G-inflation, containing yet further generalization of Ginf lation, as well as previous examples such as k-inflation, extended inflation, and new Higgs inflation as special cases.
Abstract: We study generalized Galileons as a framework to develop the most general single-field inflation models ever, Generalized G-inflation, containing yet further generalization of Ginf lation, as well as previous examples such as k-inflation, extended inflation, and new Higgs inflation as special cases. We investigate the background and perturbation evolution in this model, calculating the most general quadratic actions for tensor and scalar cosmological perturbations to give the stability criteria and the power spectra of primordial fluctuations. It is pointed out in the Appendix that the Horndeski theory and the generalized Galileons are equivalent. In particular, even the non-minimal coupling to the Gauss-Bonnet term is included in the generalized Galileons in a non-trivial manner. Subject Index: 440, 442, 453
1,093 citations
TL;DR: In this article, a truncated moment formalism for general relativistic radiation hydrodynamics, based on Thorne's moments formalism, is derived, and the fluid rest frame is chosen to be the fiducial frame for defining the radiation moments.
Abstract: A truncated moment formalism for general relativistic radiation hydrodynamics, based on Thorne’s moment formalism, is derived. The fluid rest frame is chosen to be the fiducial frame for defining the radiation moments. Then, zeroth-, first-, and second-rank radiation moments are defined from the distribution function with a physically reasonable assumption for it in the optically thin and thick limits. The source terms are written, focusing specifically on the neutrino transfer and neglecting higher harmonic angular dependence of the reaction angle. Finally, basic equations for a truncated moment formalism for general relativistic radiation hydrodynamics in a closed covariant form are derived assuming a closure relation among the radiation stress tensor, energy density, and energy flux, and a variable Eddington factor, which works well. Subject Index: 451, 480, 483
165 citations
102 citations
TL;DR: The current observational and experimental bounds on the time variation of the constants of nature (the fine structure constant, the gravitational constant, and the proton-electron mass ratio) are reviewed in this paper.
Abstract: The current observational and experimental bounds on the time variation of the constants of nature (the fine structure constant $\alpha$, the gravitational constant $G$ and the proton-electron mass ratio $\mu=m_p/m_e$) are reviewed.
91 citations
TL;DR: In this paper, the authors investigated the cosmic microwave background (CMB) bispectra of the intensity and polarization modes induced by the graviton non-Gaussianities, which arise from the parity-conserving and parity-violating Weyl cubic terms with time-dependent coupling.
Abstract: In this chapter, we investigate the cosmic microwave background (CMB) bispectra of the intensity (temperature) and polarization modes induced by the graviton non-Gaussianities, which arise from the parity-conserving and parity-violating Weyl cubic terms with time-dependent coupling. By considering the time-dependent coupling, we find that even in the exact de Sitter space-time, the parity violation still appears in the three-point function of the primordial gravitational waves and could become large. Through the estimation of the CMB bispectra, we demonstrate that the signals generated from the parity-conserving and parity-violating terms appear in completely different configurations of multipoles. This signal is just good evidence of the parity violation in the non-Gaussianity of primordial gravitational waves. We find that the shape of this non-Gaussianity is similar to the so-called equilateral one. We naively estimate the observational bound on the model parameters.
88 citations
TL;DR: In this paper, a reverse pathway of the asymmetric dark matter scenario is proposed to generate a suitable baryon asymmetry from the hidden sector, and the asymmetry of dark matter is partially transferred into the standard model sector.
Abstract: We propose a novel mechanism to generate a suitable baryon asymmetry from dark (hidden) sector. This is a Baryogenesis through a reverse pathway of the “asymmetric dark matter” scenario. In the mechanism, the asymmetry of dark matter is generated at first, and it is partially transferred into a baryon asymmetry in the standard model sector. This mechanism enables us not only to realize the generation of the baryon asymmetry but also to account for the correct amount of dark matter density in the present universe within a simple framework.
88 citations
TL;DR: In this article, the authors provide an in-depth analysis of the most representative mirroring techniques used in SPH to enforce boundary conditions (BC) along solid profiles, specifically refer to dunimy particles, ghost particles, and Takeda et al. boundary integrais.
Abstract: The aim of the present work is to provide an in-depth analysis of the most representative mirroring techniques used in SPH to enforce boundary conditions (BC) along solid profiles. We specifically refer to dunimy particles, ghost particles, and Takeda et al. [Prog. Theor. Phys. 92 (1994), 939] boundary integrais. The analysis has been carried out by studying the convergence of the first- and second-order differential operators as the smoothing length (that is, the characteristic length on which relies the SPH interpolation) decreases. These differential operators are of fundamental importance for the computation of the viscous drag and the viscous/diffusive terms in the momentum and energy equations. It has been proved that ciose to the boundaries some of the mirroring techniques leads to intrinsic inaccuracies in the convergence of the differential operators. A consistent formulation has been derived starting from Takeda et al. 1' boundary integrais (see the above reference). This original formulation allows implementing no-slip boundary conditions consistently in many practical applications as viscous flows and diffusion problems. Subject Index: 024 The Smoothed Particle Hydrodynamics scheme (hereinafter SPH) is a Lagrangian model based on a smoothing of the spatial differential operators of the fluid-dynamics equations and on their subsequent discretization through a finite number of fluid par ticles. The smoothing procedure (which is made at the continuum level) is performed by using a weight function (also called kernel function) with a compact support whose characteristic length is the smoothing length h. After the smoothed equations are discretized through fluid particles, the resolution of the discrete SPH scheme is a function of both the smoothing length and the mean particle distance dx. In this framework, the (continuous) equations of the fluid-dynamics should be recovered as both h and dx/h tend simultaneously to zero. 4) The SPH simulations in engineering involve usually solid boundary conditions (BC) for the velocity field and Dirichlet and Neumann type BC for other fields as, for instance, the temperature. In the SPH framework, these conditions are tackled in a number of ways: by using boundary forces-type models;5) by modifying the structure of the kernel in the neighborhood of the boundaries;6) by creating virtual
83 citations
TL;DR: In this article, a lattice formulation of a mass-deformed two-dimensional N = (8, 8) super Yang-Mills theory with preserving two supercharges exactly is presented.
Abstract: We construct a lattice formulation of a mass-deformed two-dimensional N = (8, 8) super Yang-Mills theory with preserving two supercharges exactly. Gauge fields are represented by compact unitary link variables, and the exact supercharges on the lattice are nilpotent up to gauge transformations and SU(2)R rotations. Due to the mass deformation, the lattice model is free from the vacuum degeneracy problem, which was encountered in earlier approaches, and flat directions of scalar fields are stabilized giving discrete minima representing fuzzy S. Around the trivial minimum, quantum continuum theory is obtained with no tuning, which serves a nonperturbative construction of the IIA matrix string theory. Moreover, around the minimum of k-coincident fuzzy spheres, four-dimensional N = 4 U(k) super Yang-Mills theory with two commutative and two noncommutative directions emerges. In this theory, sixteen supersymmetries are broken by the mass deformation to two. Assuming the breaking is soft, we give a scenario leading to undeformed N = 4 super Yang-Mills on R without any fine tuning. As an evidence for the validity of the assumption, some computation of 1-loop radiative corrections is presented.
75 citations
TL;DR: In this paper, an all-sky formalism for the CMB bispectrum induced by the primordial non-Gaussianities not only in scalar but also in vector and tensor fluctuations is presented.
Abstract: We present an all-sky formalism for the Cosmic Microwave Background (CMB) bispectrum induced by the primordial non-Gaussianities not only in scalar but also in vector and tensor fluctuations. We find that the bispectrum can be formed in an explicitly rationally invariant way by taking into account the angular and polarization dependences of the vector and tensor modes. To demonstrate this and present how to use our formalism, we consider a specific example of the correlation between two scalars and a graviton as the source of non-Gaussianity. As a result, we show that the CMB reduced bispectrum of the intensity anisotropies is evaluated as a function of the multipole and the coupling constant between two scalars and a graviton denoted by gtss; |b��� |∼ � −4 × 8 × 10 −18 |gtss|. By estimating the signal-to-noise ratio, we find that the constraint as |gtss| < 6 will be expected from the PLANCK experiment. Subject Index: 400, 435, 440, 442, 451
68 citations
TL;DR: In this paper, the elastic cross section of general vector dark matter with nucleon in the direct detection at the leading order of the strong coupling constant was studied, assuming that the dark matter is composed of vector particles.
Abstract: In this paper we complete formulae for the elastic cross section of general vector dark matter with nucleon in the direct detection at the leading order of the strong coupling constant, assuming that the dark matter is composed of vector particles. As an application of our formulae, the direct detection of the first Kaluza-Klein photon in the minimal universal extra dimension model is discussed. It is found that the cross section is larger than those in the previous works by up to a factor of ten.
67 citations
TL;DR: In this paper, all quantal systems related to the exceptional Laguerre and Jacobi polynomials can be constructed in a direct and systematic way, without the need of shape invariance and Darboux-Crum transformation.
Abstract: We show how all the quantal systems related to the exceptional Laguerre and Jacobi polynomials can be constructed in a direct and systematic way, without the need of shape invariance and Darboux-Crum transformation. Furthermore, the prepotential need not be assumed a priori. The prepotential, the deforming function, the potential, the eigenfunctions and eigenvalues are all derived within the same framework. The exceptional polynomials are expressible as a bilinear combination of a deformation function and its derivative. Subject Index: 010, 064
TL;DR: In this article, the authors presented a paper on the physics and mathematics of the universe in the High Energy Accelerator Research Organization (KEK) of the Japanese National Institute of Particle and Nuclear Studies.
Abstract: 1KEK Theory Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801, Japan 2Graduate School of Pure and Applied Sciences, University of Tsukuba, Tsukuba 305-8571, Japan 3Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan 4Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan 5Institute for the Physics and Mathematics of the Universe (IPMU), The University of Tokyo, Kashiwa 277-8583, Japan
TL;DR: In this article, the exceptional q-Racah polynomials were constructed, together with the exceptional Laguerre, Jacobi, Wilson and Askey-Wilson polynomorphisms.
Abstract: The exceptional Racah and q-Racah polynomials are constructed. Together with the exceptional Laguerre, Jacobi, Wilson and Askey-Wilson polynomials discovered by the present authors in 2009, they exhaust the generic exceptional orthogonal polynomials of a single variable.
TL;DR: In this paper, a modification of Crum's theorem and its modification a la Krein-Adler are formulated for the discrete quantum mechanics with real shifts, whose eigenfunctions consist of orthogonal polynomials of a discrete variable.
Abstract: Crum’s theorem and its modification a la Krein-Adler are formulated for the discrete quantum mechanics with real shifts, whose eigenfunctions consist of orthogonal polynomials of a discrete variable. The modification produces the associated polynomials with a finite number of degrees deleted. This in turn provides the well known Christoffel transformation for the dual orthogonal polynomials with the corresponding positions deleted.
TL;DR: In this paper, a solution of the IKKT matrix model with structure R 3,1 × K is presented, where the noncommutativity relates the compact with the non-compact space.
Abstract: Solutions of the undeformed IKKT matrix model with structure R 3,1 × K are presented, where the noncommutativity relates the compact with the non-compact space. The extra dimensions are stabilized by angular momentum, and the scales of K are generic moduli of the solutions. Explicit solutions are given for K = T 2 ,K = T 4 ,K = S 2 × T 2 and K = S 2 × S 2 . Infinite towers of Kaluza-Klein modes may arise in some directions, along with an effective UV cutoff on the non-compact space. Deformations of these solutions carry NC gauge theory coupled to (emergent) gravity. Analogous solutions of the BFSS model are also given. Subject Index: 125, 138, 141
TL;DR: In this article, the index theorem of the Dirac operator was extended to matrix models and non-commutative spaces with finite degrees of freedom, using a Ginsparg-Wilson relation developed in the lattice gauge theory.
Abstract: Matrix models are a promising candidate to formulate the superstring theory nonperturbatively,1),2) and they indeed include quantum gravity and gauge theory. One of the important subjects in such studies is to connect these models to phenomenology. Spacetime structures can be analyzed dynamically in the IIB matrix model,3) and four dimensionality seems to be preferred.3),4) Assuming that fourdimensional spacetime is obtained, we next want to show the standard model of particle physics on it. An important ingredient of the standard model is the chirality of fermions. Chirality also ensures the existence of massless fermions, since, otherwise, quantum corrections would induce mass of the order of the Planck scale or of the Kaluza-Klein scale in general. A way to obtain chiral spectrum in our spacetime is to consider topologically nontrivial configurations in the extra dimensions.∗∗) Owing to the index theorem,7) the topological charge of the background provides the index of the Dirac operator, i.e., the difference in the numbers of chiral zero modes, which then produce massless chiral fermions on our spacetime. Generalizations of the index theorem to matrix models or noncommutative (NC) spaces with finite degrees of freedom were provided by using a Ginsparg-Wilson (GW) relation∗∗∗) developed in the lattice gauge theory.11) In M4 × S2 × S2 embeddings in the IIB matrix model, however, we could not obtain a chiral spectrum on M4, even though the IIB matrix model is chiral in ten dimensions, and topological configurations give chiral zero modes on S2 × S2, since
TL;DR: In this paper, it was shown that the IR divergence is absent in the genuine gauge-invariant quantity at the leading order in the slow-roll approximation, and that the spurious IR divergence originates from the careless treatment of the gauge modes.
Abstract: It has been an issue of debate whether the inflationary infrared (IR) divergences are physical or not. Our claim is that, at least, in single-field models, the answer is “No”, and that the spurious IR divergence is originating from the careless treatment of the gauge modes. In our previous work we have explicitly shown that the IR divergence is absent in the genuine gauge-invariant quantity at the leading order in the slow-roll approximation. We extend our argument to include higher-order slow-roll corrections and the contributions from the gravitational waves. The key issue is to assure the gauge invariance in the choice of the initial vacuum, which is a new concept that has not been considered in conventional calculations.
TL;DR: In this paper, the authors revisited the hybrid inflation model focusing on the dynamics of the waterfall field in an analytical way, and showed that inflation may last long enough during the waterfall regime for some parameter regions, confirming the claim of Clesse.
Abstract: We revisit the hybrid inflation model focusing on the dynamics of the waterfall field in an analytical way. It is shown that inflation may last long enough during the waterfall regime for some parameter regions, confirming the claim of Clesse. In this case the scalar spectral index becomes red, and can fall into the best fit range of the WMAP observation. Subject Index: 442
TL;DR: In this article, the effects of sudden change in the sound velocity on primordial curvature perturbation spectrum in inflationary cosmology were studied, assuming that the background evolution satisfies the slow-roll condition throughout.
Abstract: We study the effects of sudden change in the sound velocity on primordial curvature perturbation spectrum in inflationary cosmology, assuming that the background evolution satisfies the slow-roll condition throughout. It is found that the power spectrum acquires oscillating features which are determined by the ratio of the sound speed before and after the transition and the wavenumeber which crosses the sound horizon at the transition, and their analytic expression is given. In some values of those parameters, the oscillating primordial power spectrum can better fit the observed Cosmic Microwave Background temperature anisotropy power spectrum than the simple power-law power spectrum, although introduction of such a new degree of freedom is not justified in the context of Akaike’s Information Criterion. Subject Index: 400, 436, 440, 442
TL;DR: In this paper, the authors study constraints to avoid deep unrealistic minima in the next-to-minimal supersymmetric standard model and show that a wide and significant region of the parameter space, especially large regions, is ruled out by their constraints.
Abstract: We study constraints to avoid deep unrealistic minima in the next-to-minimal supersymmetric standard model. We analyze a scalar potential along directions where all of and one of the three Higgs fields develop their vacuum expectation values, and find unrealistic minima deeper than the electroweak symmetry breaking (EWSB) vacuum. These unrealistic minima threaten the realization of the successful EWSB and therefore should be avoided. Necessary conditions to avoid these minima result in constraints of parameters. We show that a wide and significant region of the parameter space, especially large �, is ruled out by our constraints.
TL;DR: In this paper, the authors constructed an exact solution for the spherical gravitational collapse in asingle coordinate patch using ageneralized form of the Painleve-Gullstrand coordinates in the Schwarzschildspacetime.
Abstract: We construct an exact solution for the spherical gravitational collapse in asingle coordinate patch To describe the dynamics of collapse, we use ageneralized form of the Painleve-Gullstrand coordinates in the Schwarzschildspacetime The time coordinate of the form is the proper time of a free-fallingobserver so that we can describe the collapsing star not only outside but alsoinside the event horizon in a single coordinate patch We show the bothsolutions corresponding to the gravitational collapse from infinity and from afinite radius
TL;DR: In this article, it was shown that the entropy field can generate the observable fluctuations, which cannot be eliminated by gauge transformations in the local universe, which is referred to as genuine gauge invariance.
Abstract: In recent publications we proposed one way to calculate gauge-invariant variables in a local observable universe which is limited to a portion of the whole universe. To provide a theoretical prediction of the observable fluctuations, we need to preserve the gauge-invariance in the local universe, which is referred to the genuine gauge-invariance. The importance of the genuine gauge invariance is highlighted in the study of primordial fluctuations in the infrared (IR) limit. The stability against IR loop corrections to primordial fluctuations is guaranteed in requesting the genuine gauge invariance. The genuine gauge-invariance also gives impacts on the detectable fluctuations. We showed that at observable scales the bispectrum calculated in the conventional perturbation theory vanishes in the squeezed limit, if we request the genuine gauge invariance. This indicates that the conventional bi-spectrum is, in this limit, dominated by a gauge artifact, which cannot be observed. These studies have been elaborated in single-field models of inflation. In this paper we generalize our argument to multi-field models of inflation, where, in addition to the adiabatic field, the entropy field can participate in the generation of primordial fluctuations. We will find that the entropy field can generate the observable fluctuations, which cannot be eliminated by gauge transformations in the local universe. Subject Index: 440, 442
TL;DR: Tatsumi Aoyama, Jun Nishimura, and Toshiyuki Okubo as discussed by the authors proposed a method to solve the problem of high energy acceleration in the high energy accelerator at the University of Nagoya.
Abstract: Tatsumi Aoyama,1 Jun Nishimura2,3,∗) and Toshiyuki Okubo4,∗∗) 1Kobayashi-Maskawa Institute for the Origin of Particles and the Universe (KMI), Nagoya University, Nagoya 464-8602, Japan 2KEK Theory Center, High Energy Accelerator Research Organization, Tsukuba 305-0801, Japan 3The Graduate University for Advanced Studies (SOKENDAI), Tsukuba 305-0801, Japan 4Faculty of Science and Technology, Meijo University, Nagoya 468-8502, Japan
TL;DR: An approach toward the laboratory search for the scalar field as a candidate of dark energy was proposed by Fujii and Homma as mentioned in this paper, who used the concept of scalar fields as a reference point for the dark energy search.
Abstract: An approach toward the laboratory search for the scalar field as a candidate of dark energy Yasunori Fujii1 and Kensuke Homma2,3,∗ 1Advanced Research Institute for Science and Engineering, Waseda University, Okubo, Tokyo 169-8555, Japan 2Graduate School of Science, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan 3International Center for Zetta-Exawatt Science and Technology, Ecole Polytechnique, Route de Saclay, Palaiseau, F-91128, France ∗E-mail: homma@hepl.hiroshima-u.ac.jp
TL;DR: In this paper, the authors calculate the CMB statistically anisotropic bispectrum sourced from the curvature perturbations generated in the modified hybrid inflation scenario and find the peculiar configurations of the multipoles which never appear in the isotropic bispectra, like off-diagonal components in the cMB power spectrum.
Abstract: There have been many works that verify the possibility of the small deviation of the statistical isotropy, e.g., the so-called “Axis of Evil”. The analyses of the power spectrum by employing the current CMB data suggest that the deviation of the statistical isotropy is about 10 % at most. As is well known, it might be difficult to explain such statistical anisotropy in the standard inflationary scenario. However, recently, there have been several works about the possibility of generating the statistically anisotropic primordial density fluctuations in order to introduce nontrivial dynamics of the vector field. Owing to the effect of fluctuations of the vector field, the primordial density fluctuations may have a small deviation from the statistical isotropy and also the deviation from the Gaussian statistics. Hence, we can expect that there are characteristic signals not only in the CMB power spectrum but also in the CMB bispectrum. With these motivations, we calculate the CMB statistically anisotropic bispectrum sourced from the curvature perturbations generated in the modified hybrid inflation scenario. Then, we find the peculiar configurations of the multipoles which never appear in the isotropic bispectrum, like off-diagonal components in the CMB power spectrum.
TL;DR: In this paper, the volume of moduli space of BPS vortices on a compact genus h Riemann surface was evaluated by using topological field theory and localization technique developed by Moore, Nekrasov and Shatashvili.
Abstract: We evaluate volume of moduli space of BPS vortices on a compact genus h Riemann surface Σh by using topological field theory and localization technique developed by Moore, Nekrasov and Shatashvili. We apply this technique to Abelian (ANO) vortex and show that the volume of moduli space agrees with the previous results obtained by integrating over the moduli space metric. We extend the evaluation to non-Abelian gauge groups and multi
TL;DR: In this article, the universal properties of second order phase transition in holographic superconductor models were studied using a simple analytic approach, and the relation between the critical temperature and the charge density was analyzed analytically.
Abstract: By using a simple analytic approach, we study the universal properties of second order phase transition in holographic superconductor models. We explore a general model in arbitrary dimen- sions that the condensation occurs via the Stuckelberg spontaneous symmetry breaking mechanism. All possible second order phase transitions and their universal characters can be identified analyt- ically. The relation between the critical temperature and the charge density is generic, and the critical exponents can be greater than the typical mean field value 1/2. In addition, the related numerical factors can also be computed qualitatively.
TL;DR: In this paper, a two-qubit gate with the JaynesCummings model was proposed, where a photon is running on a pair of optical paths, and a nonlinear sign-shift gate was constructed with small error probability in principle.
Abstract: In this paper, we propose a method for building a two-qubit gate with the JaynesCummings model (JCM). In our scheme, we construct a qubit from a pair of optical paths where a photon is running. Generating Knill, Laflamme and Milburn’s nonlinear sign-shift gate by the JCM, we construct the conditional sign-flip gate, which works with small error probability in principle. We also discuss two experimental setups for realizing our scheme. In the first experimental setup, we make use of coherent lights to examine whether or not our scheme works. In the second experimental setup, an optical loop circuit made out of the polarizing beam splitter and the Pockels cell takes an important role in the cavity. Subject Index: 061
TL;DR: In this paper, the authors proposed a method to use the Paterna method to solve the problem of nuclear energy and nuclear energy engineering in Nara Women's University, Nara 630-8506, Japan.
Abstract: 1Department of Physics, Nara Women’s University, Nara 630-8506, Japan 2Departamento de Fisica Teorica and IFIC, Centro Mixto Universidad de Valencia-CSIC, Institutos de Investigacion de Paterna, Aptdo 22085, 46071 Valencia, Spain 3Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan 4Nishina Center for Accelerator-Based Science, RIKEN, Wako 351-0198, Japan 5School of Physics and Nuclear Energy Engineering, Beihang University, Beijing 100191, China 6Physik Department, Technische Universitat Munchen, D-85747 Garching, Germany
TL;DR: The one-pion exchange current corrections to isoscalar and isovector magnetic moments of double-closed shell nuclei plus and minus one nucleon with A = 15, 17, 39 and 41 have been studied in the relativistic mean field (RMF) theory as discussed by the authors.
Abstract: The one-pion exchange current corrections to isoscalar and isovector magnetic moments of double-closed shell nuclei plus and minus one nucleon with A = 15, 17, 39 and 41 have been studied in the relativistic mean field (RMF) theory and compared with previous relativistic and non-relativistic results. It has been found that the one-pion exchange current gives a negligible contribution to the isoscalar magnetic moments but a significant correction to the isovector ones. However, the one-pion exchange current doesn’t improve the description of nuclear isovector magnetic moments for the concerned nuclei. PACS numbers: 21.10.Ky, 21.30.Fe, 21.60.Jz ∗Electronic address: mengj@pku.edu.cn