A MICROSCOPIC CALCULATION OF SECONDARY DRELL-YAN PRODUCTION IN HEAVY-ION COLLISIONS

A study of secondary Drell-Yan production in nuclear collisions is pre sented for SPS energies. In addition to the lepton pairs produced in t he initial collisions of the projectile and target nucleons, we consid er the potentially high dilepton yield from hard valence antiquarks in produced mesons and antibaryons. We calculate the secondary Drell-Yan contributions taking the collision spectrum of hadrons from the micro scopic model URQMD. The contributions from meson-baryon interactions, small in hadron-nucleus interactions, are found to be substantial in n ucleus-nucleus collisions at low dilepton masses. Preresonance collisi ons of partons may further increase the yields.