Self-T-Dual Brane Cosmology and the Cosmological Constant Problem

TL;DR

This paper explores a brane cosmology model with T-duality symmetry that self-tunes the cosmological constant, avoids singularities via a bounce, and suggests a mechanism for an ever-expanding universe.

Contribution

It introduces a T-duality symmetric brane model with self-tuning properties and a bouncing cosmology, providing new insights into the cosmological constant problem.

Findings

Self-tuning of the brane vacuum energy independent of Poincaré invariance

Presence of a cosmological bounce avoiding singularities

Construction of an ever-expanding universe via T-duality symmetry

Abstract

We consider a codimension-one brane embedded in a gravity-dilaton bulk action, whose symmetries are compatible with T-duality along the space-like directions parallel to the brane, and the bulk time-like direction. The equations of motions in the string frame allow for a smooth background obtained by the union of two symmetric patches of AdS space. The Poincar\'{e} invariance of the solution appears to hold independently of the value of the brane vacuum energy, through a self-tuning property of the dilaton ground state. Moreover, the effective cosmology displays a bounce, at which the scale factor does not shrink to zero. Finally, by exploiting the T-duality symmetry, we show how to construct an ever-expanding Universe, along the lines of the Pre-Big Bang scenario.