Electron-positron pairs from thermal resonances in ultrarelativistic nuclear collisions

We use a boost-invariant one-dimensional (cylindrically symmetric) fluid dynamics code to calculate e(+)e(-) production from rho(0) and omega decay in the central rapidity region of a central S+Au collision at root s=20 GeV/nucleon. We use equations of state with a first-order phase transition between a massless pion gas and quark gluon plasma, with transition temperatures in the range 150-200 MeV. The production cross section at the rho mass loosely constrains the transition and freeze-out temperature, and we find that the m(T) spectrum is a good thermometer for sufficiently high T-c.