Black Hole Bound on the Number of Species and Quantum Gravity at LHC

TL;DR

The paper discusses how a large number of particle species affects black hole physics, proposing a bound that influences the hierarchy problem and predicts black hole behavior at the LHC.

Contribution

It introduces a black hole bound on the number of species, linking it to the hierarchy problem and the quantum gravity scale, with implications for black hole decay signatures.

Findings

Black hole bound constrains species number to stabilize the hierarchy.

Effective gravitational cutoff is reduced to M_{Planck}/√N.

Black holes at LHC predominantly decay into Standard Model particles.

Abstract

In theories with a large number N of particle species, black hole physics imposes an upper bound on the mass of the species equal to M_{Planck}/\sqrt{N}. This bound suggests a novel solution to the hierarchy problem in which there are N \approx 10^{32} gravitationally coupled species, for example 10^{32} copies of the Standard Model. The black hole bound forces them to be at the weak scale, hence providing a stable hierarchy. We present various arguments, that in such theories the effective gravitational cutoff is reduced to \Lambda_G \approx M_{Planck}/\sqrt{N} and a new description is needed around this scale. In particular black-holes smaller than \Lambda_G^{-1} are already no longer semi-classical. The nature of the completion is model dependent. One natural possibility is that \Lambda_G is the quantum gravity scale. We provide evidence that within this type of scenarios, contrary to the standard intuition, micro black holes have a (slowly-fading) memory of the species of origin. Consequently the black holes produced at LHC, will predominantly decay into the Standard Model particles, and negligibly into the other species.