1992851
FIVE-DIMENSIONAL KALUZA–KLEIN THEORY WITH A SOURCE
A free test particle in five-dimensional Kaluza–Klein space–time will show its electricity in the reduced four-dimensional space–time when it moves along the fifth dimension. In the light of this observation, we study the coupling of a five-dimensional dust field with the Kaluza–Klein gravity. It turns out that the dust field can curve the five-dimensional space–time in such a way that it provides exactly the source of the electromagnetic field in the four-dimensional space–time after the dimensional reduction.
119211222
Separation of space–time and matter in polar oscillations of compact stars
In polar oscillations of compact stars dynamical changes in spacetime and matter are in general coupled together. Based on the theory of stellar pulsation proposed by Allen et al. [Phys. Rev. D 58, 124012 (1998)], we establish a feasible approximation scheme to separate spacetime from matter in such oscillations. Two independent second-order ordinary differential equations are obtained, which lead to accurate determination of p-mode and w-mode quasi-normal modes of compact stars, respectively.
118631921
Small scale aspects of warm dark matter : power spectra and acoustic oscillations.
We provide a semianalytic derivation of approximate evolution equations for density perturbations of warm dark matter candidates that decoupled while relativistic with arbitrary distribution functions, their solutions at small scales, and a simple numerical implementation that yields their transfer functions and power spectra. Density perturbations evolve through three stages: radiation domination when the particle is relativistic and nonrelativistic and matter domination. An early integrated Sachs-Wolfe effect during the first stage leads to an enhancement of density perturbations and a plateau in the transfer function for k or approx. 2k{sub fs}. A simple analytic interpolation of the power spectra between large and small scales and a numerical implementation valid for arbitrary distribution functions is provided. As an application we study the power spectra for two models of sterile neutrinos with m{approx}keV produced nonresonantly and compare our results to those obtained from Boltzmann codes.
119240361
High-frequency behavior of w-mode pulsations of compact stars
We study the asymptotic behavior of the quasinormal modes (QNMs) of $w$-mode pulsations of compact stars in the high-frequency regime. We observe that both the axial and polar $w$-mode QNMs attain similar asymptotic behaviors in spite of the fact that they are described by two totally different differential equation systems. We obtain robust asymptotic formulas relating $w$-mode QNMs of different polarities and different angular momenta. To explore the physical reason underlying such similarity, we first derive a high-frequency approximation for the polar $w$-mode oscillations to unify the descriptions for both cases. Then, we develop WKB-type analyses for them and quantitatively explain the observed asymptotic behaviors for polytropic stars and quark stars. We also point out that such asymptotic behaviors for realistic stars are strongly dependent on the equation of state near the stellar surface.
15649438
Generalized inverse-Cowling approximation for polar w-mode oscillations of neutron stars
Adopting the Lindblom-Detweiler formalism for polar oscillations of neutron stars, we study the w-mode oscillation and find that the Lagrangian change in pressure, measured by the physical quantity X, is negligibly small. Based on this observation, we develop the generalized inverse-Cowling approximation (GICA) with the approximation X = X' = 0, where X' is the derivative of X with respect to the circumferential radius for w-mode oscillations of neutron stars. Under the GICA, w-mode oscillations are described by a second-order differential system, which can yield accurate frequencies and damping rates of quasi-normal modes.
119349480
Determination of the internal structure of neutron stars from gravitational wave spectra
In this paper the internal structure of a neutron star is shown to be inferrable from its gravitational-wave spectrum. Iteratively applying the inverse scheme of the scaled coordinate logarithmic perturbation method for neutron stars proposed by Tsui and Leung [Astrophys. J. {\bf 631}, 495 (2005)], we are able to determine the mass, the radius and the mass distribution of a star from its quasi-normal mode frequencies of stellar pulsation. In addition, accurate equation of state of nuclear matter can be obtained from such inversion scheme. Explicit formulas for the case of axial $w$-mode oscillation are derived here and numerical results for neutron stars characterized by different equations of state are shown.
119522047
Lattice calculation of nucleon axial form factors
Abstract Preliminary results on the isovector and isoscalar axial-vector form factors of the proton from a lattice QCD calculation are presented and discussed. The results are based on a quenched 16 3 × 24 lattice at β = 6.0 with Wilson fermions at κ = 0.152. Results from the smeared source are compared with those from the point source. It is found that the smeared source gives somewhat better results at zero momentum transfer but worse results at high momentum transfers. Our results also suggest that the quark loop contribution to the flavor-singlet axial-vector current may play an important role in understanding the quark-spin content of the proton as determined from the recent EMC experiment.
118072068
Calogero-Sutherland model in interacting fermion picture and explicit construction of Jack states
The 40-year-old Calogero-Sutherland (CS) model remains a source of inspirations for understanding 1d interacting fermions. At $\beta=1, \text{or}0$, the CS model describes a free non-relativistic fermion, or boson theory, while for generic $\beta$, the system can be interpreted either as interacting fermions or bosons, or free anyons depending on the context. However, we shall show in this letter that the fermionic picture is advantageous in diagonalizing the CS Hamiltonian. Comparing to the previously known multi-integral representation or the Dunkl operator formalism for the CS wave functions, our method depends on the (upper or lower) triangular nature of the fermion interaction, which is resolved in perturbation theory of the second quantized form. The eigenstate is constructed from a multiplet of unperturbed states and the perturbation is of finite order. The full construction is a similarity transformation from the free fermion theory, in the same spirit as the Landau Fermi liquid theory and the 1d Luttinger liquid theory. That means quasi-particles or anyons can be represented in terms of free fermion modes (or bosonic modes via bosonization). The method is applicable to other (higher than one space dimension) systems for which the adiabatic theorem applies.
118665852
Holographic lattice in Einstein-Maxwell-dilaton gravity
A bstractWe construct an ionic lattice background in the framework of Einstein-Maxwell-dilaton theory in four dimensional space time. The optical conductivity of the dual field theory on the boundary is investigated. Due to the lattice effects, we find the imaginary part of the conductivity is manifestly suppressed in the zero frequency limit, while the DC conductivity approaches a finite value such that the previous delta function reflecting the translation symmetry is absent. Such a behavior can be exactly fit by the Drude law at low frequency. Moreover, we find that the modulus of the optical conductivity exhibits a power-law behavior at intermediate frequency regime. Our results provides further support for the universality of such power-law behavior recently disclosed in Einstein-Maxwell theory by Horowitz, Santos and Tong.
41474583
The Spectrum of the Hybrid Mesons with Heavy Quarks from the B . S . Equation
We construct the B.S. equation for the hybrid mesons under instantaneous approximation. The kernel is chosen as the sum of an one-gluon exchange potential and a linear confining potential. The equations are solved by numerical method, and the spectrum of hybrid mesons bb̄g and cc̄g are obtained. PACS: 14.40.C, 11.10.St.
41259393
Electrostatic and magnetostatic solutions in a Lorentz-violating electrodynamics model
We propose an effective Lorentz-violating electrodynamics model via the static de Sitter metric, which is deviated from the Minkowski metric by a minuscule amount depending on the cosmological constant. We obtain the electromagnetic field equations via the vierbein decomposition of the tensors. In addition, as an application of the electromagnetic field equations obtained, we derive the solutions of the electrostatic field and the magnetostatic field due to a point charge and a circle current, respectively, and discuss the implication of the effect of Lorentz violation in our electromagnetic theory.