The role of gluons in dilepton production from the quark-gluon plasma

We study high mass dilepton production from gluon-induced processes, gq --> q gamma *, g (g) over bar --> (q) over bar gamma *, and gg --> q (q) over bar gamma *, in a thermally equilibrated but chemically undersaturated part onic matter that is expected to be created in the initial stage of ultrarel ativistic heavy ion collisions. Regulating the divergence in these processe s by the thermal quark mass, we find that gluon-induced processes are more important than the leading-order q (q) over bar annihilation process as a r esult of the larger number of gluons than quarks in the partonic matter. Th e dependence of the thermal dilepton yield from the partonic stage of heavy ion collisions on the initial conditions for the partonic matter is also s tudied. We further discuss the feasibility of observing thermal dileptons f rom the quark-gluon plasma in heavy ion experiments. (C) 2000 Published by Elsevier Science B.V. All rights reserved.