Ratio of absorption cross section for Dirac fermion to that for scalar in the higher-dimensional black hole background

TL;DR

This paper calculates the ratio of low-energy absorption cross sections for Dirac fermions and scalars in higher-dimensional Reissner-Nordström black holes, revealing that fermion absorption vanishes in the extremal limit, with implications for brane-world and string theories.

Contribution

It provides the first detailed computation of the absorption cross section ratio for fermions versus scalars in various higher-dimensional black hole backgrounds.

Findings

Fermion absorption cross section approaches zero in the extremal limit.

The ratio of absorption cross sections is computed for different black hole geometries.

Results are relevant for theories involving extra dimensions like string theory.

Abstract

The ratio of the low-energy absorption cross section for Dirac fermion to that for minimally coupled scalar is computed when the spacetimes are various types of the higher-dimensional Reissner-Nordstr\"{o}m black holes. It is found that the low-energy absorption cross sections for the Dirac fermion always goes to zero in the extremal limit regardless of the detailed geometry of the spacetime. The physical importance of our results is discussed in the context of the brane-world scenarios and string theories.