Vector spectral functions and transport properties in quenched QCD

TL;DR

This study reconstructs mesonic spectral functions in quenched QCD at three temperatures, revealing temperature independence in vector correlators and estimating electrical conductivity, with implications for dilepton production.

Contribution

It provides a continuum-extrapolated analysis of vector spectral functions in quenched QCD at multiple temperatures using improved Wilson quarks and a well-motivated fitting approach.

Findings

Vector correlation functions are nearly temperature independent.

Electrical conductivity is estimated to be between 0.2 and 0.4 times $C_{em}$.

Dilepton rates show no significant temperature dependence.

Abstract

We present new results on the reconstruction of mesonic spectral functions for three temperatures $1.1T_c$, $1.2T_c$ and $1.4T_c$ in quenched QCD. Making use of non-perturbatively improved clover Wilson valence quarks allows for a clean extrapolation of correlator data to the continuum limit. For the case of vanishing momentum the spectral function is obtained by fitting the data to a well motivated ansatz, using the full covariance matrix of the continuum extrapolated data in the fit. We found that vector correlation function is almost temperature independent in the current temperature window. The electrical conductivity of the hot medium, related to the origin of the vector spectral function at zero momentum, is computed from the resulting parameters at all three temperatures, leading to an estimate of $0.2C_{em}\lesssim \sigma/T\lesssim0.4C_{em}$. The dilepton rates resulting from the obtained spectral functions show no significant temperature dependence.