Pair creation rate for $U(1)^2$ black holes

TL;DR

This paper calculates the pair creation rate of black holes in a string theory truncation with two U(1) gauge fields, showing suppression in realistic scenarios and a relation to the Schwinger effect, with enhancement for non-extreme black holes.

Contribution

It provides a new calculation of black hole pair creation rate in a specific string theory model, extending previous Einstein-Maxwell results.

Findings

Pair creation is strongly suppressed in realistic conditions.

The rate reduces to the Schwinger result in the point-particle limit.

Non-extreme black holes are more likely to be created than extreme ones by a factor of e^{A_{bh}/4}.

Abstract

I consider a truncation of low-energy string theory which contains two $U(1)$ gauge fields. After making some general comments on the theory, I describe a previously-obtained instanton for the pair creation of black holes when both gauge fields are non-zero, and obtain the pair creation rate by calculating its action. This calculation agrees qualitatively with the earlier calculation of the pair creation rate for black holes in Einstein-Maxwell theory. That is, the pair creation is strongly suppressed in realizable circumstances, and it reduces to the Schwinger result in the point-particle limit. The pair creation of non-extreme black holes is enhanced over that of extreme black holes by $e^{{\cal A}_{bh}/4}$.