Jia-rong Li

Refractive index in the viscous quark-gluon plasma

Under the framework of the viscous chromohydrodynamics, the gluon self-energy is derived for the quark-gluon plasma with shear viscosity. The viscous chromoelectric permittivity and chromomagnetic permeability are evaluated from the gluon self-energy, through which the chromorefraction index is investigated. The numerical analysis indicates that the chromorefractive index becomes negative in some frequency range. The starting point for that frequency range is around the chromoelectric permittivity pole, and the chromomagnetic permeability pole determines the endpoint. As �=s increases, the frequency range for the negative refraction becomes wider.

The momentum analyticity of two point correlators from perturbation theory and AdS/CFT

The momentum plane analyticity of two point function of a relativistic thermal field theory at zero chemical potential is explored with both perturbative and nonperturbative method. A general principle regarding the location of t he singularities is extracted. In the case of the N = 4 supersymmetric Yang-Mills theory at large Nc, the nonperturbative nature of the singularity (simple poles) is observed in the strong coupling limit via the AdS/CFT correspondence.

Polarization energy loss in hot viscous quark–gluon plasma

The gluon polarization tensor for quark–gluon plasma with shear viscosity is derived with the viscous chromohydrodynamics. The longitudinal and transverse dielectric functions are evaluated from the gluon polarization tensor, through which the polarization energy loss suffered by a fast quark traveling through the viscous quark–gluon plasma is investigated. The numerical analysis indicates that shear viscosity significantly reduces the polarization energy loss.

The imaginary part of the gap function in color superconductivity

Abstract We clarify general properties of the energy gap regarding its functional dependence on the energy–momentum dictated by the invariance under a space inversion or a time reversal. Then we derive perturbatively the equation of the imaginary part of the gap function for dense QCD in weak coupling and generalize our results from 2SC case to CFL case. We confirm that the imaginary part is down by g relative to the real part in weak coupling. The numerical results show that, up to the leading order, the imaginary part is no larger than one MeV at extremely large densities and can be as large as several MeV for the densities of physical interest.

Energy change of high energy partons propagating through a quark-gluon plasma with fluctuations or turbulence

Abstract We calculate the energy changes of a colored particle and a color dipole passing through a quark-gluon plasma (QGP) taking into account the non-linear color dielectric coefficient and find the partons may have an increase of energy determined by fluctuating or turbulent intensity unlike the result in a linear approximation. We also show the acceleration effect is due to energy transfer into the partons from fluctuating fields.

Low shear viscosity due to Anderson localization

We study the Anderson Localization effect on the shear viscosity in a system with random medium by Kubo formula. We show that this effect can reduce the shear viscosity nonperturbatively. Then we discuss its possible implementation in heavy-ion collisions, where the created heavy bound states or other collective modes may play the role of the random scatterer underlying Anderson Localization effect.