Thermal dilepton radiation at intermediate masses at the CERN-SpS

We investigate the significance of thermal dilepton radiation in the intermediate-mass region in heavy-ion reactions at CERN-SpS energies. Within a thermal fireball model for the space-time evolution, the radiation from hot matter is found to dominate over hard ʹbackgroundʹ processes (Drell–Yan and open charm) up to invariant masses of about 2 GeV, with a moderate fraction emerging from early stages with temperatures T≃175–200 MeV associated with deconfined matter. Further including a schematic acceptance for the NA50 experiment we find good agreement with the observed enhancement in the region 1.5 GeV