No abstract

We propose a unified scaling theory of entanglement entropy in the confinements of finite bond dimensions, dynamics and system sizes. Within the theory, the finite-entanglement scaling introduced recently is generalized to the dynamics subjected to a linear driving along with a finite system size. Competition among the three scales as well as the correlation length of the system is analysed in details. Interesting regimes and their complicated crossovers together with their characteristics follow naturally. The theory is verified with the one-dimensional transverse-field Ising model under a linear driving.

The thermal properties of light mesons, including the temperature dependence of their masses (both screening and pole masses) and thermal widths, are studied in a two-flavor (Nf = 2) soft-wall AdS/QCD model. By solving the spatial correlation functions, we extract the screening masses (mscr) from their poles. The screening masses of pseudo-scalar (π) and axial-vector (a1) mesons increase almost monotonously with the increase of temperature. The screening masses of scalar (σ) and vector (ρ) mesons decrease at low temperature and increase at high temperature. The pole masses (mpole) and the thermal widths (Γ) are extracted from the temporal correlation functions and the corresponding spectral functions. The results indicate that the pole masses have local minima at low temperature and increase at high temperature. The thermal widths increase rapidly above the chiral crossover temperature Tcp, indicating the dissociations of mesons at high temperature. Furthermore, the degeneration of the chiral partners (π and σ, ρ and a1) above Tcp is observed from the screening and pole masses, revealing the chiral symmetry restoration at the hadronic spectrum level. Finally, we numerically verify that the spectral functions in the temporal regime are strongly related to the quasi-normal modes with complex frequencies ω0 = mpole− iΓ/2.

We study the phase transition between the pion condensed phase and normal phase, as well as chiral phase transition in a two flavor ( ) IR- improved soft-wall AdS/QCD model at finite isospin chemical potential and temperature T. By self-consistently solving the equations of motion, we obtain the phase diagram in the plane of and T. The pion condensation appears together with a massless Nambu-Goldstone boson , which is very likely to be a second-order phase transition with mean-field critical exponents in the small region. When , the critical isospin chemical potential approximates to vacuum pion mass . The pion condensed phase exists in an arched area, and the boundary of the chiral crossover intersects the pion condensed phase at a tri-critical point. Qualitatively, the results are in good agreement with previous studies on lattice simulations and model calculations.

Abstract. We calculate all components of thermal R-current correlators from AdS/CFT correspondence for non-zero momentum and energy. In zero momentum limit, we find an analytic expression for the components G xx (G yy ). The dielectric function of strong coupling is also presented and compared with that in weak coupling.