Brane-world black holes and the scale of gravity

TL;DR

This paper explores how brane-world effects modify black hole properties, potentially allowing microscopic black holes to form at energies accessible to the LHC, with implications for detecting extra-dimensional gravity.

Contribution

It analyzes the impact of bulk effects on black hole thresholds and suggests the possibility of black hole production at collider energies below the fundamental gravity scale.

Findings

Black holes could form at energies below the fundamental scale MG.

Bulk effects can alter the black hole mass threshold and entropy.

LHC might produce black holes even if M > 10 TeV.

Abstract

A particle in four dimensions should behave like a classical black hole if the horizon radius is larger than the Compton wavelength or, equivalently, if its degeneracy (measured by entropy in units of the Planck scale) is large. For spherically symmetric black holes in 4 + d dimensions, both arguments again lead to a mass threshold MC and degeneracy scale Mdeg of the order of the fundamental scale of gravity MG. In the brane-world, deviations from the Schwarzschild metric induced by bulk effects alter the horizon radius and effective four-dimensional Euclidean action in such a way that MC \simeq Mdeg might be either larger or smaller than MG. This opens up the possibility that black holes exist with a mass smaller than MG and might be produced at the LHC even if M>10 TeV, whereas effects due to bulk graviton exchanges remain undetectable because suppressed by inverse powers of MG. Conversely, even if black holes are not found at the LHC, it is still possible that MC>MG and MG \simeq 1TeV.