String Dilaton Fluid Cosmology

TL;DR

This paper explores higher-dimensional string-dilaton cosmology with matter, deriving exact solutions and analyzing transitions to Einstein gravity and string coupling behaviors.

Contribution

It provides exact solutions for string-dilaton cosmology with matter, highlighting the transition from string-dominated to Einstein gravity regimes.

Findings

Exact solutions parametrized by matter and curvature

Recovery of Einstein gravity from string regime

Asymptotic freedom due to string coupling

Abstract

We investigate $(n+1)$-dimensional string-dilaton cosmology with effective dilaton potential in presence of perfect-fluid matter.We get exact solutions parametrized by the constant $\gam$ of the state equation $p=(\gam-1)\rho$, the spatial dimension number $n$, the bulk of matter, and the spatial curvature constant $k$. Several interesting cosmological behaviours are selected. Finally we discuss the recovering of ordinary Einstein gravity starting from string dominated regime and a sort of asymptotic freedom due to string effective coupling.