120206017
Heavy Quark Potential and QCD Beta Function from a Deformed AdS5 Model
We show that in a deformed ${\rm AdS}_5$ model with an explicit infrared cutoff included in the logarithmic correction $-c_0\log[(z_{IR}-z)/z_{IR}]$, the heavy quark Cornell potential can be fitted very well, the corresponding beta-function agrees with the QCD beta-function at 2-loop level reasonably well, and its dual dilaton potential is bounded from below in infrared. The results are compared with those in the Andreev-Zakharov model and the Pirner-Galow model.
118646566
Pseudoscalar glueball in a chiral Lagrangian model with instanton effect
We study the pseudoscalar glueball ground state in a chiral effective Lagrangian model proposed by 't Hooft, motivated by taking into account the instanton effects, which can describe not only the chiral symmetry breaking, but also the solution of U{sub A}(1). We study the parameter space allowed by constraints from vacuum conditions and unitary bounds. By considering two scenarios in the 0{sup ++} sector, we find that parameter space which can accommodate the 0{sup -+} sector is sensitive to the conditions in 0{sup ++} sector. From our analysis, it is found that three {eta} states, i.e. {eta}(1295), {eta}(1405), {eta}(1475), can be the pseudoscalar glueball ground state if we assume that the lightest 0{sup ++} glueball ground state has a mass 1710 (or 1500) MeV. While there will be no 0{sup -+} glueball candidate ground state found in experiments if we assume that the lightest 0{sup ++} glueball ground state has a mass 660 MeV. We also point out the determined instanton density (i.e. the parameter k{sub t}) is consistent with those determined from other methods, e.g. instanton liquid approximation and lattice simulations.
118364646
Scalar Mesons and glueballs in $Dp-Dq$ hard-wall models
Chao Wang, Song He, Mei Huang, Qi-Shu Yan, and Yi Yang 1 Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, China 2 Theoretical Physics Center for Science Facilities, Chinese Academy of Sciences, Beijing, China 3 Department of Physics, University of Toronto, Toronto, Canada 4 Department of Electrophysics, National Chiao-Tung University, Hsinchu, Taiwan and 5 Physics Division, National Center for Theoretical Sciences, Hsinchu, Taiwan (Dated: February 5, 2009)
118538162
Hydrodynamics of a 5D Einstein-dilaton black hole solution and the corresponding BPS state
A bstractWe apply the potential reconstruction approach to generate a series of asymp-totically AdS (aAdS) black hole solutions, with a self-interacting bulk scalar field. Based on the method, we reproduce the pure AdS solution as a consistency check and we also generate a simple analytic 5D black hole solution. We then study various aspects of this solution, such as temperature, entropy density and conserved charges. Furthermore, we study the hydrodynamics of this black hole solution in the framework of fluid/gravity duality, e.g. the ratio of the shear viscosity to the entropy density. In a degenerate case of the 5D black hole solution, we find that the c function decreases monotonically from UV to IR as expected. Finally, we investigate the stability of the degenerate solution by studying the bosonic functional energy of the gravity and the Witten-Nester energy EWN. We confirm that the degenerate solution is a BPS domain wall solution. The corresponding superpotential and the solution of the killing spinor equation are found explicitly.
119239121
Thermodynamics of deformed AdS5 model with a positive/negative quadratic correction in graviton-dilaton system
By solving the Einstein equations of the graviton coupling with a real scalar dilaton field, we establish a general framework to self-consistently solve the geometric background with black-hole for any given phenomenological holographic models. In this framework, we solve the black-hole background, the corresponding dilaon field and the dilaton potential for the deformed AdS5 model with a positive/negative quadratic correction. We systematically investigate the thermodynamical properties of the deformed AdS5 model with a positive and negative quadratic correction, respectively, and compare with lattice QCD on the results of the equation of state, the heavy quark potential, the Polyakov loop and the spatial Wilson loop. We find that the bulk thermodynamical properties are not sensitive to the sign of the quadratic correction, and the results of both deformed holographic QCD models agree well with lattice QCD result for pure SU(3) gauge theory. However, the results from loop operators favor a positive quadratic correction, which agree well with lattice QCD result. Especially, the result from the Polyakov loop excludes the model with a negative quadratic correction in the warp factor of AdS5.
76649422
A hQCD model and its phase diagram in Einstein-Maxwell-Dilaton system
A bstractBy use of the potential reconstruction approach we obtain a series of asymptotically AdS (aAdS) black hole solutions in an Einstein-Maxwell-Dilaton (EMD) system. Basing on the solutions of the system, we reconstruct a semi-analytical holographic QCD (hQCD) model with a quadratic term in warped factor. We discuss some aspects of the hQCD model, in particular we calculate the free energy of two static color sources (a heavy quark-antiquark pair) which is an important order parameter to describe confinement/deconfinement phase transition. The behavior of the free energy with respect to temperature and chemical potential is studied. We find that in the hQCD model the deconfinement phase transition can be realized and a critical point occurs. The resulting phase diagram in the temperature-chemical potential T − μ plane is in quite good agreement with the one from recent lattice results and effective models of QCD.
119513103
Quantum entanglement of electromagnetic field in non-inertial reference frames
Recently relativistic quantum information has received considerable attention due to its theoretical importance and practical application. In particular, quantum entanglement in non-inertial reference frames has been studied for scalar and Dirac fields. As a further step along this line, we here shall investigate quantum entanglement of electromagnetic field in non-inertial reference frames. In particular, the entanglement of the photon helicity entangled state is extensively analysed. Interestingly, the resultant logarithmic negativity and mutual information remain the same as those for inertial reference frames, which is completely different from that previously obtained for the particle number entangled state.
67757844
Null Polygonal Wilson Loops in Full N=4 Superspace
We compute the one-loop expectation value of light-like polygonal Wilson loops in N = 4 super-Yang{Mills theory in full superspace. When projecting to chiral superspace we recover the known results for tree-level next-to-maximally-helicity-violating (NMHV) scattering amplitude. The one-loop MHV amplitude is also included in our result but there are additional terms which do not immediately correspond to scattering amplitudes. We nally discuss dierent regularizations and their Yangian anomalies.
118339656
Note on new KLT relations
In this short note, we present two results about KLT relations discussed in recent several papers. Our first result is the re-derivation of Mason-Skinner MHV amplitude by applying the Sn−3 permutation symmetric KLT relations directly to MHV amplitude. Our second result is the equivalence proof of the newly discovered Sn−2 permutation symmetric KLT relations and the well-known Sn−3 permutation symmetric KLT relations. Although both formulas have been shown to be correct by BCFW recursion relations, our result is the first direct check using the regularized definition of the new formula.
7012367
A COVARIANT ENTROPY BOUND CONJECTURE ON THE DYNAMICAL HORIZON
We propose, as a compelling pattern for the holographic principle, a covariant entropy bound conjecture for more general dynamical horizons. Then we apply our conjecture to ΛCDM cosmological models, where we find that it imposes a novel upper bound, 10-90, on the cosmological constant for our own universe by taking into account the dominant entropy contribution from supermassive black holes, which thus provides an alternative macroscopic perspective for understanding the long-standing cosmological constant problem. As an intriguing implication of this conjecture, we also discuss the possible profound relation between the present cosmological constant, the origin of mass, and the anthropic principle.
17450923
Anisotropic Lattice Calculation of Pion Scattering Using an Asymmetric Box
Pion-pion elastic scattering phase shifts in the I = 2, J = 0 channel are calculated within quenched approximation using improved gauge and Wilson fermion actions on anisotropic lattices in an asymmetric box. Using the modified Lüscher’s formula applicable in an asymmetric volume, we are able to access more low-momentum modes than a cubic box with similar volume. The calculation is performed at three lattice spacings at β = 2.080, β = 2.215 and β = 2.492. For each lattice spacing, several valence quark mass values are taken in the quenched approximation which enable us to extrapolate the results to the chiral limit. Continuum limit extrapolation is then performed and the extrapolated results are compared with the known results from both theory and experiment. We find that our lattice results for the scattering phase shifts in this channel are consistent with the experimental data when the three-momentum of the pion is below 300MeV. The results are Preprint submitted to Elsevier 2 March 2008 also consistent with previous lattice calculations and other theoretical calculations using Chiral Perturbation Theory or dispersion relations. We have also given the pion-pion scattering length in the chiral and continuum limit.