Seminar in Hadronic Physics

Shedding light on photon and dilepton spectral functions

Greg Jackson

University of Bern

Photons and dileptons offer themselves as ‘clean’ probes of the quark-gluon plasma because they are unlikely to reinteract once produced. Their emission rates are given via the vector channel spectral function, an object that can ultimately be reconstructed by analytic continuation of lattice data. To confront perturbative results with that data, the NLO corrections are needed in all domains that affect the associated imaginary-time correlator, namely for energies above, below and in the vicinity of the light cone. We summarize recent progress here and, to control an unavoidable snag, we also determine these corrections for the transverse and longitudinal polarizations separately. Our results help to scrutinize direct spectral reconstruction attempts from lattice QCD.