EVOLUTION OF NEAR-EXTREMAL BLACK-HOLES

Near-extreme black holes can lose their charge and decay by the emissi on of massive Bogomol'ni-Prasad-Sommerfield charged particles. We calc ulate the greybody factors for low-energy charged and neutral scalar e mission from four- and five-dimensional near extremal Reissner-Nordstr om black holes. We use the corresponding emission rates to obtain rati os of the rates of loss of excess energy by charged and neutral emissi on, which are moduli independent, depending only on the integral charg es and the horizon potentials. We consider scattering experiments, fin ding that evolution towards a state in which the integral charges are equal is favored, but neutral emission will dominate the decay back to extremality except when one charge is much greater than the others. T he implications of our results for the agrement between black hole and D-brane emission rates and for the information loss puzzle an then di scussed.