Enhancement of intermediate mass dileptons from expanding hot quark-gluon matter

A study of the production of intermediate mass dileptons from the quark phase and hadronic interactions as wen as nonthermal contributions (Drell-Yan pairs, charmed hadronic decays) in the initial stage has been carried out based on a relativistic hydrodynamic model describing the evolution of a quark-gluon matter fire-cylinder. We find that due to the influence of the phase boundary on the evolution of the quark-gluon matter system and the high initial temperature of the quark-gluon matter produced at RHIC energies, the contribution of the quark phase to dileptons is obviously enhanced and is more important than those from hadronc interactions and even is comparable with those from nonthermal contributions. It is shown that the enhancement of intermediate mass dileptons is a possible signature for the quark-gluon matter formation in heavy ion collisions at RHIC energies.