Dielectric And Dissipative Properties Of Strong Interaction Matter

Relativistic heavy ion collision is a significant experimental tool for deep understanding of the strong interaction. Scientists expect to create enough high temperature environment in the collision and realize the transition from nuclear matter to quark matter. This dissertation mainly forces on the two phases of the transition, i.e., the nuclear and quark matter phase, and investigate their dielectric and dissipative properties by employing the finite temperature field theory and kinetics theory.At the beginning, we briefly review the status of heavy ion collision, both in experimental and theoretical aspects. Then some important definitions and methods are introduced one by one, including the decomposition of gauge propagator and polarization tensor, hard thermal loop and effective perturbation, transport equation, the medium effects in linear response and two frameworks which are involved in the calculations of QGP shear viscosity.As to nuclear matter, we discuss its dielectric functions induced by rho meson polarization, pointing out that the basic characters are the two extrema appear in the space-like and time-like region on the curve which can be explained by the Landau damping and current induced by resonant excitations of in-medium nucleons, respectively. Considering domination of theρNN tensor coupling, we study the dielectric function at finite temperature and chemical potential in this coupling form, which clearly shows the two asymmetric extrema that emerge at the point of two times nucleon effective mass in the time-like region are contributed by the nucleons and anti-nucleons near the Fermi surface. The asymmetry is getting more and more obvious with the raising temperature due to the smear of the Fermi surface.For quark matter, scalar QCD is employed to describe the coupling between gauge field and colored bound state in strongly-coupled QGP. As a toy model, we discuss the dielectric functions of QED+sQED, compare the hard thermal loop and complete one-loop calculations on polarization. The comparison suggests the complete one-loop embodies the hard external momentum contribution compared to the hard thermal loop and thus demonstrates a non-trivial structure in the time-like region. Still in this region, the dielectric function of sQED approaches to the vacuum value in its real part and deviates from the unit around the point of two times mass of bound state, which implies an energy transfer between the collective mode and bosonic bound state. When considering the gauge plasma with scalar bound states, the two opposite tendencies between QED and sQED would compete and brings the total dielectric function fruitful structures.The shear viscosity of weakly-coupled QGP is obtained through kinetics theory and Kubo formula at finite temperature and chemical potential. The results show the chemical potential effect enhances the shear viscosity by adding a correction ofμ~2/T~2 to the pure temperature case. In Kubo formula, the effective width of in-medium particle is introduced to regular the infrared behavior of one-loop skeleton diagram, which leads to the same parameter dependencies of leading-log order as those in the kinetics framework. Besides, a maximum estimation of the velocity gradient is performed by adopting Bjorken's evolutional scenario and thus entropy density production is obtained. The result show, although in the linear response framework, the entropy production is not as small as one may expect. We also present the ratio of shear viscosity to the non-equilibrium entropy density with respect to the coupling strength, which suggest, on one side, the ratio exists only in a physical region which constrains the weak coupling to a lower limit. On the other side, the ratio is at least two times larger than the one extracted by fitting data, which means the weak coupling fails to explain the RHIC experiment and strong coupling or long distance correlation is likely to be involved.As for strongly coupled QGP, We propose to calculate the in-medium particle potential by employing the complete one-loop resummation effective propagator when dealing with the gauge plasma with scalar bound states. The obtained potential exhibits an oscillatory behavior with damping amplitude, which is different with Debye screening from hard thermal loop resummation. The oscillatory potential is relevant to four parameters including the temperature, the mass of fermion, the mass of scalar bound state and the coupling strength. They belong to two categories which have distinguished tendencies and contribute to the potential in two opposite directions. The competition between the parameters in the two categories may lead the potential enough long in distance and strong in strength thus guarantee a proper potential to produce liquid state in QGP.