PAIR CREATION OF DILATON BLACK-HOLES

We consider dilaton gravity theories in four spacetime dimensions para metrized by a constant a, which controls the dilaton coupling, and con struct new exact solutions. We first generalize the C metric of Einste in-Maxwell theory (a = 0) to solutions corresponding to oppositely cha rged dilaton black holes undergoing uniform acceleration for general a . We next develop a solution-generating technique which allows us to ' 'embed'' the dilaton C metrics in magnetic dilaton Melvin backgrounds, thus generalizing the Ernst metric of Einstein-Maxwell theory. By adj usting the parameters appropriately, it is possible to eliminate the n odal singularities of the dilaton C metrics. For a < 1 (but not for a greater-than-or-equal-to 1), it is possible to further restrict the pa rameters so that the dilaton Ernst solutions have a smooth Euclidean s ection with topology S2 x S2 - {pt}, corresponding to instantons descr ibing the pair production of dilaton black holes in a magnetic field. A different restriction on the parameters leads to smooth instantons f or all values of a with topology S2 x R2.