Dr Olaf Kaczmarek (University Bielefeld)

Hadronic Correlation and Spectral Functions in the QGP

I will discuss properties of hadronic excitations at high temperature by investigating hadron correlation functions for light as well as charm quarks in the deconfined phase of quenched QCD. We have performed a systematic analysis of the influence of cut-off effects on light quark meson correlators at T=1.5 T_c using clover improved Wilson fermions on quenched gauge field configurations. We check that finite volume effects are small compared to the significant cut-off dependence observed in the correlation functions. The continuum extrapolation of these correlators are seen to be well under control for distances 0.2 < τ T < 0.5. We discuss consequences for the determination of hadronic spectral functions and the analysis of their low energy structure. In the light quark sector this leads to the determination of the dilepton rates and an estimate on the electrical conductivity. For charm quarks we discuss the determination of heavy quark diffusion constants and estimates on the dissociation of charmonium states in the plasma.