Magnetic Black Holes in String Theory

TL;DR

This paper investigates how string-loop corrections affect magnetic black hole solutions in string theory, revealing that quantum effects can smooth out classical singularities in the effective four-dimensional supergravity framework.

Contribution

It provides a detailed calculation of loop corrections to magnetic black hole solutions within N=2 supergravity, demonstrating the smearing of singularities due to quantum effects.

Findings

Loop corrections modify gauge couplings at small r.

Quantum effects smear classical singularities.

Perturbative solutions show regularized black hole metrics.

Abstract

We discuss the form of the string-loop-corrected effective action and the loop-corrected solutions of the equations of motion. At the string-tree level, a solution we consider is the extremal magnetic black hole, in which case the tree-level effective gauge couplings decrease at small r, and in this region string-loop corrections to the gauge couplings become important. The effective 4D theory is the N=2 supergravity interacting with matter. Using the N=2 structure of the theory, we calculate the loop corrections to the effective action and solve the loop-corrected equations of motion. In the resulting perturbative solution for the metric, singularity at the origin is smeared by quantum effects.