THERMAL QUARK PRODUCTION IN PURE GLUE AND QUARK-GLUON PLASMAS

We calculate production rates for massless (u, d) and massive (s, c, b) quarks in pure glue and quark-gluon plasmas to leading order in the strong coupling constant g. The leading contribution comes from gluon decay into qqBAR pairs using a thermal gluon propagator with finite thermal mass and damping rate. The rate behaves as alpha(s)2(In1/alpha(s))2T4 when m, alpha(s) --> 0 and depends linearly on the gluon damping rate for all values of the quark mass m. The light quark (u, d, s) chemical equilibration time is approximately 10-100 T-1 for g = 2-3, so that quarks are likely to remain far from chemical equilibrium in ultra-relativistic nuclear collisions.