Observing many-body effects on lepton pair production from low mass enhancement and flow at RHIC and LHC energies

The ρ spectral function at finite temperature calculated using the real-time formalism of thermal field theory is used to evaluate the low mass dilepton spectra. The analytic structure of the ρ propagator is studied and contributions to the dilepton yield in the region below the bare ρ peak from the different cuts in the spectral function are discussed. The space-time integrated yield shows significant enhancement in the region below the bare ρ peak in the invariant mass spectra. It is argued that the variation of the inverse slope of the transverse mass ( M T ) distribution can be used as an efficient tool to predict the presence of two different phases of the matter during the evolution of the system. The sensitivities of the effective temperature obtained from the slopes of the M T spectra to the medium effects are studied.