Hadronic Spectral Functions above the QCD Phase Transition

TL;DR

This study uses the maximum entropy method on anisotropic lattice QCD data to analyze spectral functions above the deconfinement temperature, revealing persistent structures and a phase change in the quark-gluon plasma.

Contribution

First application of MEM to extract hadronic spectral functions above Tc on anisotropic lattices with detailed temperature dependence.

Findings

Spectral functions show non-trivial structures above Tc.

Qualitative change in deconfined matter occurs between 1.5 Tc and 2 Tc.

Persistent spectral features suggest complex quark-gluon interactions.

Abstract

We extract the spectral functions in the scalar, pseudo-scalar, vector, and axial vector channels above the deconfinement phase transition temperature (Tc) using the maximum entropy method (MEM). We use anisotropic lattices, 32^3 * 32, 40, 54, 72, 80, and 96 (corresponding to T = 2.3 Tc --> 0.8 Tc), with the renormalized anisotropy xi = 4.0 to have enough temporal data points to carry out the MEM analysis. Our result suggests that the spectral functions continue to possess non-trivial structures even above Tc and in addition that there is a qualitative change in the state of the deconfined matter between 1.5 Tc and 2 Tc.