S-Wave Scattering of Charged Fermions by a Magnetic Black Hole

TL;DR

This paper investigates quantum scattering of charged fermions by magnetically charged black holes, revealing backscattering effects and Hawking radiation suppression near extremality, with a focus on extremal dilatonic black holes.

Contribution

It provides a perturbative, unitary S-matrix description of backscattering for extremal dilatonic black holes with a single fermion flavor, highlighting quantum effects on classical absorption.

Findings

Backscattering described by a perturbative, unitary S-matrix.

Hawking radiation is suppressed near extremality.

Classical absorption probability is unity for s-wave electrons.

Abstract

We argue that, classically, $s$-wave electrons incident on a magnetically charged black hole are swallowed with probability one: the reflection coefficient vanishes. However, quantum effects can lead to both electromagnetic and gravitational backscattering. We show that, for the case of extremal, magnetically charged, dilatonic black holes and a single flavor of low-energy charged particles, this backscattering is described by a perturbatively computable and unitary $S$-matrix, and that the Hawking radiation in these modes is suppressed near extremality. The interesting and much more difficult case of several flavors is also discussed.