Exact Solutions and the Cosmological Constant Problem in Dilatonic-Domain-Wall Higher-Curvature String Gravity

TL;DR

This paper explores exact solutions in higher-curvature string gravity models with branes, aiming to address the cosmological constant problem and mass hierarchy through dilatonic domain walls and holographic techniques.

Contribution

It extends previous work by analyzing solutions with higher-curvature corrections in brane worlds, focusing on dilatonic domain walls and their implications for cosmology.

Findings

Dilatonic domain wall solutions can resolve naked singularities via holography.

The models suggest a link between brane tension, string coupling, and vacuum energy.

A coordinate transformation reveals a linear dilaton CFT structure.

Abstract

In this article we extend previous work by the authors, and elaborate further on the structure of the general solution to the graviton and dilaton equations of motion in brane world scenaria, in the context of five-dimensional effective actions with O(\alpha ')$ higher-curvature corrections, compatible with bulk string-amplitude calculations. We consider (multi)brane scenaria, dividing the bulk space into regions, in which one matches two classes of general solutions, a linear Randall-Sundrum solution and a (logarithmic) dilatonic domain wall (bulk naked singularity).We pay particular attention to examining the possibility of resolving the mass hierarchy problem together with the vanishing of the vacuum energy on the observable world, which is taken to be a positive tension brane. The appearance of naked dilatonic domain walls provides a dynamical restriction of the bulk space time. Of particular interest is a dilatonic-wall solution, which after appropriate coordinate transformation, results in a linear dilaton conformal field theory. The latter may provide a holographic resolution of the naked singularity problem. All the string-inspired models involved have the generic feature that the brane tensions are proportional to the string coupling $g_s$; it remains a challenge for string theory, therefore, to show whether microscopic models respecting this feature can be constructed.