Temperature dependence of electrical conductivity and dilepton rates from hot quenched lattice QCD

Abstract

We present new results on the continuum extrapolation of the vector current correlation function in the deconfined phase for three temperatures close to the critical temperature utilizing quenched clover improved Wilson fermions and light quark masses. A systematic analysis on multiple lattice spacing allows to perform the continuum limit of the correlation function and to extract spectral properties in the continuum limit. These results provide constraints for the electrical conductivity and the thermal dilepton rates in the quark gluon plasma for the given temperature range. In addition results on the continuum extrapolation at finite momenta related to thermal photon rates are presented.

Electrical conductivity and charge diffusion in thermal QCD from the lattice

“…In the following we neglect the disconnected pieces, which is expected to have a small effect, since their contribution is identically zero in the (degenerate) N f = 3 case (since f q f = 0). We note that the same choice has been made in all previous studies [18][19][20][21][22]. Finally, as we have shown in section 4, the contribution from disconnected diagrams to the charge susceptibility is negligible.…”

“…The first results were obtained using the staggered fermion formulation [18,19] in quenched QCD. Since then the study of the systematic uncertainties and the extension to Wilsontype quarks have taken a central role, in quenched QCD [20,21] and in dynamical QCD with N f = 2 and 2 + 1 flavours [22,23]. All studies [19][20][21][22][23] are in qualitative agreement: around T = 1.5T c , where T c is the crossover temperature, the conductivity is of the order of σ = 0.2 − 0.4C em T c , where C em is an electromagnetic prefactor depending on the quark charges (see section 5 below).…”

“…For this we follow the same procedure as in our previous work [19,23], namely the Maximum Entropy Method (MEM) [65]. Other possibilities in- clude the use of a physically motivated Ansatz for the spectral function, with a number of parameters to be determined [20][21][22], as well as alternative inversion methods [66][67][68].…”

Electromagnetic radiation in hot QCD matter: Rates, electric conductivity, flavor susceptibility, and diffusion

“…In Fig. 6 the electric conductivities from a hadronic gas are compared with recent lattice results [21,30] and the lower bound [31] which are discussed in Sec. III B.…”

Thermodynamics of Strong-Interaction Matter from Lattice QCD

“…These results have been extended to three different temperatures recently. [161][162][163] In these calculations the thermal spectral functions are obtained by fitting the continuum-extrapolated two-point Euclidean correlation functions to an ansatz for the spectral function that is motivated by kinetic theory and perturbation theory…”