A thermal instability for positive brane cosmological constant in the Randall-Sundrum cosmologies

TL;DR

This paper introduces a new mechanism in Randall-Sundrum cosmologies where a positive four-dimensional cosmological constant causes thermal radiation emission from the brane into the bulk, potentially reducing the cosmological constant.

Contribution

It presents a novel dynamical process involving bulk gravitational modes that effectively radiate away positive cosmological constants in brane-world scenarios.

Findings

Thermal radiation temperature is nonzero only for positive cosmological constant.

The brane acts as a mirror for certain bulk gravitational modes.

The mechanism can reduce vacuum energy in theories with variable vacuum energy.

Abstract

We describe a novel dynamical mechanism to radiate away a positive four dimensional cosmological constant, in the Randall-Sundrum cosmological scenario. We show that there are modes of the bulk gravitational field for which the brane is effectively a mirror. This will generally give rise to an emission of thermal radiation from the brane into the bulk. The temperature turns out to be nonvanishing only if the effective four dimensional cosmological constant is positive. In any theory where the four dimensional vacuum energy is a function of physical degrees of freedom, there is then a mechanism that radiates away any positive four dimensional cosmological constant.