  The $\rho$ 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 $\rho$ propagator is studied
and contributions to the dilepton yield in the region below the bare $\rho$
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 $\rho$ 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. Sensitivity of the effective
temperature obtained from the slopes of the $M_T$ spectra to the medium effects
are studied.
