S-DUALITY AND THE ENTROPY OF BLACK HOLES IN HETEROTIC STRING THEORY

TL;DR

This paper demonstrates that in heterotic string theory, the partition functions and entropies of electrically and magnetically charged black holes are equivalent under S-duality, with entropy vanishing in the extremal limit.

Contribution

It shows the invariance of black hole entropy and partition functions under S-duality transformations in heterotic string theory.

Findings

Partition functions are identical for dual black holes.

Black hole entropy vanishes in the extremal limit.

S-duality relates electrically and magnetically charged solutions.

Abstract

Four dimensional heterotic string effective action is known to admit non-rotating electrically and magnetically charged black hole solutions. It is shown that the partition functions and entropies in both the cases are identical when these black hole solutions are related by S-duality transformations. The entropy is computed and is vanishing for each black hole in the extremal limit.