Friedmann branes with variable tension

TL;DR

This paper develops a formalism for brane-world models with variable tension, inspired by fluid membrane physics, enabling evolving gravitational and cosmological constants that could explain dark energy.

Contribution

It introduces a covariant framework for branes with non-constant tension, including asymmetric embeddings and non-standard fields, extending previous fixed-tension models.

Findings

Formalism for variable tension branes established

Application to Friedmann branes in charged Vaidya-AdS space

Potential explanation for dark energy through evolving constants

Abstract

We introduce brane-worlds with non-constant tension, strenghtening the analogy with fluid membranes, which exhibit a temperature-dependence according to the empirical law established by E\"otv\"os. This new degree of freedom allows for evolving gravitational and cosmological constants, the latter being a natural candidate for dark energy. We establish the covariant dynamics on a brane with variable tension in full generality, by considering asymmetrically embedded branes and allowing for non-standard model fields in the 5-dimensional space-time. Then we apply the formalism for a perfect fluid on a Friedmann brane, which is embedded in a 5-dimensional charged Vaidya-Anti de Sitter space-time.