121435769
Phase Structure of Strange Matter in a Non-topological Soliton Model
A non-topological soliton model with strange quarks is suggested to investigate the phase structure of strange matter. The results are qualitatively in agreement with that obtained by MIT bag model provided the ratio of coupling constants of different quarks to soliton scalar field chi(sigma) = g(s sigma)/g(q sigma) larger than a critical value chi(c) similar to 0.86, but as chi(sigma) gets smaller than chi(c), the phase structure may change.
121746713
The effective mass and screening mass of the rho meson for the vector dominance model and the vector coupling model at finite temperature and density
In the framework of thermo-field dynamics, the temperature and/or density dependences of the effective mass and the screening mass of the rho -meson for the vector dominance model and the nucleon-nucleon- rho -meson (NN rho ) vector coupling model have been calculated. We have found that for the vector dominance model, the effective mass and the screening mass of the rho -meson increase with temperature, and for the NN rho vector coupling model, they remain almost unchanged with temperature, but increase with density.
120297881
Thermodynamical fluctuations of meson fields for the Zimanyi-Moszkowski model
By using the real-time Green{close_quote}s function method with a pair cutoff approximation up to the second order, the thermodynamical fluctuation effects of meson fields on the Zimanyi-Moszkowski model are investigated. We find that in the fluctuation effects on the effective mass of the nucleon, the pressures are considerable in the low-baryon-density region and/or the high-temperature regions. The results of the Zimanyi-Moszkowski model and the Welecka model beyond the mean-field approximation are compared. {copyright} {ital 1997} {ital The American Physical Society}
124303693
Effective Masses of Mesons and Nucleon in Hot Medium for the Walecka Model
Based on the thermo-field dynamics, the temperature and density dependencies of the effective masses of σ, ω mesons and nucleon in the walecka model have been calculated. The vacuum fluctuation effect is examined. It is found that the vacuum fluctuation is very important and leads to a reduction of ω-meson mass and an enhancement of σ-meson mass in hot and dense medium.
119297362
Holographic forced fluid dynamics in non-relativistic limit
We study the thermodynamics and non-relativistic hydrodynamics of the holographic fluid on a finite cutoff surface in the Gauss-Bonnet gravity. It is shown that the isentropic flow of the fluid is equivalent to a radial component of gravitational field equations. We use the non-relativistic fluid expansion method to study the Einstein-Maxwell-dilaton system with a negative cosmological constant, and obtain the holographic incompressible forced Navier-Stokes equations of the dual fluid at AdS boundary and at a finite cutoff surface, respectively. The concrete forms of external forces are given. (c) 2012 Elsevier B.V. All rights reserved.
122762455
TeV Gamma Ray Survey on the Direction of Fermi-LAT Pulsars with the Tibet Air Shower Array
We search for steady TeV γ-rays from 18 pulsars in the Fermi-LAT pulsar catalog using the Tibet air shower array. We observe 8 sources including the Crab against expected 0.41 sources at a significance of 2σ or more among the 18 pulsars. The chance probability from Poisson statistics is estimated to be 1.4×10-8.With the Crab excluded, it is estimated to be 1.8×10-7. These low chance probabilities clearly show that the Fermi pulsars have a statistically significant correlation with TeV γ-ray excesses observed by the Tibet air shower array.
119165682
Electroweak cogenesis
A bstractWe propose a simple renormalizable model of baryogenesis and asymmetric dark matter generation at the electroweak phase transition. Our setup utilizes the two Higgs doublet model plus two complex gauge singlets, the lighter of which is stable dark matter. The dark matter is charged under a global symmetry that is broken in the early universe but restored during the electroweak phase transition. Because the ratio of baryon and dark matter asymmetries is controlled by model parameters, the dark matter need not be light. Thus, new force carriers are unnecessary and the symmetric dark matter abundance can be eliminated via Higgs portal interactions alone. Our model places a rough upper bound on the dark matter mass, and has implications for direct detection experiments and particle colliders.
17260983
Differences in high $p_t$ meson production between CERN SPS and RHIC heavy ion collisions
In this talk we present a perturbative QCD improved parton model calculation for light meson production in high energy heavy ion collisions. In order to describe the experimental data properly, one needs to augment the standard pQCD model by the transverse momentum distribution of partons ("intrinsic k_T"). Proton-nucleus data indicate the presence of nuclear shadowing and multiscattering effects. Further corrections are needed in nucleus-nucleus collisions to explain the observed reduction of the cross section. We introduce the idea of proton dissociation and compare our calculations with the SPS and RHIC experimental data.
119108763
Magnetic field effect on the phase transition in AdS soliton spacetime
We investigate the scalar perturbations in an anti-de Sitter soliton background coupled to a Maxwell field via marginally stable modes. In the probe limit, we study the magnetic field effect on the holographic insulator/superconductor phase transition numerically and analytically. The condensate will be localized in a finite circular region for any finite constant magnetic field. Near the critical point, we find that there exists a simple relation among the critical chemical potential, magnetic field, the charge, and mass of the scalar field. This relation indicates that the presence of the magnetic field causes the transition from insulator to superconductor to be difficult.