Correlation functions of the energy-momentum tensor in SU(2) gauge theory at finite temperature

Abstract

We calculate correlation functions of the energy-momentum tensor in the vicinity of the deconfinement phase transition of (3 þ 1)-dimensional SU(2) gauge theory and discuss their critical behavior in the vicinity of the second order deconfinement transition. We show that correlation functions of the trace of the energy-momentum tensor diverge uniformly at the critical point in proportion to the specific heat singularity. Correlation functions of the pressure, on the other hand, stay finite at the critical point. We discuss the consequences of these findings for the analysis of transport coefficients, in particular, the bulk viscosity, in the vicinity of a second order phase transition point.

Temperature dependent transport coefficients in a dynamical holographic QCD model

“…In the perturbative region, the bulk viscosity ζ is very small and the leading dependence on α s is ζ ∝ α 2 s / ln α −1 s [28]. However, ζ/s is shown to rise sharply near T c in studies from different approaches, for example, Lattice QCD [29][30][31][32], the linear sigma model [33], the Polyakov-loop linear sigma model [34] and the real scalar model [35]. The near phase transition enhancement of bulk viscosity corresponds to the peak of trace anomaly around T c , which shows the equation of state is highly nonconformal [36,37] around phase transition.…”

Spectral densities for hot QCD plasmas in a leading-log approximation

“…Nevertheless, the urgent need for non-perturbative information about transport and other real time processes is evident from the strenuous analysis of available lattice data by several groups [21][22][23][24][25][26]. In an effort to characterize the response more completely, a number of lattice groups have begun to simulate the current-current correlators at finite spatial momentum [27,28], which reveals the real time information hidden in the Euclidean data as far as possible.…”

The shear channel spectral function in hot Yang-Mills theory

“…In addition, our results can immediately be used to evaluate the Euclidean imaginary time correlator, a quantity that has been addressed in several recent lattice and AdS/CFT calculations in both the shear and bulk channels (see e.g. [24][25][26][27][28][29], some of which also address spatial correlators). The outline of our paper is as follows.…”