Asymmetric radiating brane-world

TL;DR

This paper explores asymmetric brane-world models where differing bulk properties affect graviton emission and dark radiation levels, potentially easing cosmological constraints and revealing new energy dynamics.

Contribution

It generalizes previous symmetric models by introducing asymmetry in bulk cosmological constants and black hole masses, analyzing their effects on brane-world cosmology.

Findings

Asymmetry suppresses dark radiation levels, easing nucleosynthesis constraints.

Models with radiation escaping to infinity can have negative brane energy density.

Asymmetry influences graviton emission and black hole dynamics in brane-world scenarios.

Abstract

At high energies on a cosmological brane of Randall-Sundrum type, particle interactions can produce gravitons that are emitted into the bulk and that can feed a bulk black hole. We generalize previous investigations of such radiating brane-worlds by allowing for a breaking of Z_2-symmetry, via different bulk cosmological constants and different initial black hole masses on either side of the brane. One of the notable features of asymmetry is a suppression of the asymptotic level of dark radiation, which means that nucleosynthesis constraints are easier to satisfy. There are also models where the radiation escapes to infinity on one or both sides, rather than falling into a black hole, but these models can have negative energy density on the brane.