Calculating dilepton rates from Monte Carlo simulations of parton production

To calculate dilepton rates in a Monte Carlo simulation of ultrarelativistic heavy ion collisions, one can scale the number of similar QCD processes by a ratio of the corresponding differential probabilities. We derive the formula for such a ratio especially for dilepton bremsstrahlung processes. We also discuss the nontriviality of including higher order corrections to the direct Drell-Yan process. The resultant mass spectra from our Monte Carlo simulation are consistent with the semianalytical calculation using dilepton fragmentation functions