Remarks on effective action and entanglement entropy of Maxwell field in generic gauge

We analyze the dependence of the effective action and the entanglement entropy in the Maxwell theory on the gauge fixing parameter $a$ in $d$ dimensions. For a generic value of $a$ the corresponding vector operator is nonminimal. The operator can be diagonalized in terms of the transverse and longitudinal modes. Using this factorization we obtain an expression for the heat kernel coefficients of the nonminimal operator in terms of the coefficients of two minimal Beltrami-Laplace operators acting on 0- and 1-forms. This expression agrees with an earlier result by Gilkey et al. Working in a regularization scheme with the dimensionful UV regulators we introduce three different regulators: for transverse, longitudinal and ghost modes, respectively. We then show that the effective action and the entanglement entropy do not depend on the gauge fixing parameter $a$ provided the certain ($a$-dependent) relations are imposed on the regulators. Comparing the entanglement entropy with the black hole entropy expressed in terms of the induced Newton's constant we conclude that their difference, the so-called Kabat's contact term, does not depend on the gauge fixing parameter $a$. We consider this as an indication of gauge invariance of the contact term.Comment: 15 pages; v2: typos in eqs. (31), (32), (34), (36) corrected; discussion in section 6 expande

Global behavior of cosmological dynamics with interacting Veneziano ghost

In this paper, we shall study the dynamical behavior of the universe accelerated by the so called Veneziano ghost dark energy component locally and globally by using the linearization and nullcline method developed in this paper. The energy density is generalized to be proportional to the Hawking temperature defined on the trapping horizon instead of Hubble horizon of the Friedmann-Robertson-Walker (FRW) universe. We also give a prediction of the fate of the universe and present the bifurcation phenomenon of the dynamical system of the universe. It seems that the universe could be dominated by dark energy at present in some region of the parameter space.Comment: 8 pages, 7 figures, accepted for publication in JHE

The Rydberg-Atom-Cavity Axion Search

We report on the present progress in development of the dark matter axion search experiment with Rydberg-atom-cavity detectors in Kyoto, CARRACK I and CARRACK II. The axion search has been performed with CARRACK I in the 8 % mass range around $10 \mu {\rm eV}$, and CARRACK II is now ready for the search in the wide range $2 \mu {\rm eV} - 50 \mu {\rm eV}$. We have also developed quantum theoretical calculations on the axion-photon-atom system in the resonant cavity in order to estimate precisely the detection sensitivity for the axion signal. Some essential features on the axion-photon-atom interaction are clarified, which provide the optimum experimental setup for the axion search.Comment: 8 pages, 2 figures, Invited talk presented at the Dark2000, Heidelberg, Germany,10-15 July, 200

Holographic two dimensional QCD and Chern-Simons term

We present a holographic realization of large Nc massless QCD in two dimensions using a D2/D8 brane construction. The flavor axial anomaly is dual to a three dimensional Chern-Simons term which turns out to be of leading order, and it affects the meson spectrum and holographic renormalization in crucial ways. The massless flavor bosons that exist in the spectrum are found to decouple from the heavier mesons, in agreement with the general lore of non-Abelian bosonization. We also show that an external dynamical photon acquires a mass through the three dimensional Chern-Simons term as expected from the Schwinger mechanism. Massless two dimensional QCD at large Nc exhibits anti-vector-meson dominance due to the axial anomaly.Comment: 22 page

The mu problem and sneutrino inflation

We consider sneutrino inflation and post-inflation cosmology in the singlet extension of the MSSM with approximate Peccei-Quinn(PQ) symmetry, assuming that supersymmetry breaking is mediated by gauge interaction. The PQ symmetry is broken by the intermediate-scale VEVs of two flaton fields, which are determined by the interplay between radiative flaton soft masses and higher order terms. Then, from the flaton VEVs, we obtain the correct mu term and the right-handed(RH) neutrino masses for see-saw mechanism. We show that the RH sneutrino with non-minimal gravity coupling drives inflation, thanks to the same flaton coupling giving rise to the RH neutrino mass. After inflation, extra vector-like states, that are responsible for the radiative breaking of the PQ symmetry, results in thermal inflation with the flaton field, solving the gravitino problem caused by high reheating temperature. Our model predicts the spectral index to be n_s\simeq 0.96 due to the additional efoldings from thermal inflation. We show that a right dark matter abundance comes from the gravitino of 100 keV mass and a successful baryogenesis is possible via Affleck-Dine leptogenesis.Comment: 27 pages, no figures, To appear in JHE

Sparticle Spectrum of Large Volume Compactification

We examine the large volume compactification of Type IIB string theory or its F theory limit and the associated supersymmetry breakdown and soft terms. It is crucial to incorporate the loop-induced moduli mixing, originating from radiative corrections to the Kahler potential. We show that in the presence of moduli mixing, soft scalar masses generically receive a D-term contribution of the order of the gravitino mass m_{3/2} when the visible sector cycle is stabilized by the D-term potential of an anomalous U(1) gauge symmetry, while the moduli-mediated gaugino masses and A-parameters tend to be of the order of m_{3/2}/8pi^2. It is noticed also that a too large moduli mixing can destabilize the large volume solution by making it a saddle point.Comment: 29 page

Neutralino versus axion/axino cold dark matter in the 19 parameter SUGRA model

We calculate the relic abundance of thermally produced neutralino cold dark matter in the general 19 parameter supergravity (SUGRA-19) model. A scan over GUT scale parameters reveals that models with a bino-like neutralino typically give rise to a dark matter density \Omega_{\tz_1}h^2\sim 1-1000, i.e. between 1 and 4 orders of magnitude higher than the measured value. Models with higgsino or wino cold dark matter can yield the correct relic density, but mainly for neutralino masses around 700-1300 GeV. Models with mixed bino-wino or bino-higgsino CDM, or models with dominant co-annihilation or A-resonance annihilation can yield the correct abundance, but such cases are extremely hard to generate using a general scan over GUT scale parameters; this is indicative of high fine-tuning of the relic abundance in these cases. Requiring that m_{\tz_1}\alt 500 GeV (as a rough naturalness requirement) gives rise to a minimal probably dip in parameter space at the measured CDM abundance. For comparison, we also scan over mSUGRA space with four free parameters. Finally, we investigate the Peccei-Quinn augmented MSSM with mixed axion/axino cold dark matter. In this case, the relic abundance agrees more naturally with the measured value. In light of our cumulative results, we conclude that future axion searches should probe much more broadly in axion mass, and deeper into the axion coupling.Comment: 23 pages including 17 .eps figure

Reaction rates and transport in neutron stars

Understanding signals from neutron stars requires knowledge about the transport inside the star. We review the transport properties and the underlying reaction rates of dense hadronic and quark matter in the crust and the core of neutron stars and point out open problems and future directions.Comment: 74 pages; commissioned for the book "Physics and Astrophysics of Neutron Stars", NewCompStar COST Action MP1304; version 3: minor changes, references updated, overview graphic added in the introduction, improvements in Sec IV.A.

Peccei-Quinn extended gauge-mediation model with vector-like matter

We construct a gauge-mediated SUSY breaking model with vector-like matters combined with the Peccei-Quinn mechanism to solve the strong CP problem. The Peccei-Quinn symmetry plays an essential role for generating sizable masses for the vector-like matters and the $\mu$-term without introducing dangerous CP angle. The model naturally explains both the 125GeV Higgs mass and the muon anomalous magnetic moment. The stabilization of the Peccei-Quinn scalar and the cosmology of the saxion and axino are also discussed.Comment: 33 pages, 5 figures; version to be published (JHEP