Scattering of a scalar field in the four-dimensional quasi-topological gravity

TL;DR

This paper investigates how a massless scalar field scatters in regular black hole spacetimes from four-dimensional quasi-topological gravity, finding minimal deviations from Schwarzschild black holes in grey-body factors.

Contribution

It provides the first analysis of grey-body factors in four-dimensional quasi-topological gravity black holes using WKB approximation.

Findings

Grey-body factors are similar to Schwarzschild case, with slight deviations.

Scattering properties are insensitive to near-horizon regularization.

Quasinormal modes closely match grey-body factors for higher multipoles.

Abstract

We study grey-body factors for a massless scalar field in the spacetime of regular black holes arising in four-dimensional non-polynomial quasi-topological gravity. We consider two representative metrics that capture the typical features of regular geometries. Using the WKB method, we compute the transmission probabilities and analyze their dependence on the regularization parameter. The grey-body factors are found to deviate only slightly from the Schwarzschild case, indicating that the scattering properties are largely insensitive to near-horizon regularization of the geometry. The correspondence between quasinormal modes and grey-body factors is shown to be sufficiently accurate for higher multipole numbers.