A Non-Singular Universe in String Cosmology

Abstract

We consider the low-energy effective string action in four dimensions including the leading order-${\alpha }^{\prime }$ terms. An exact homogeneous solution is obtained. It represents a non-singular expanding cosmological model in which the tensor fields tend to vanish as $t\to \infty$. The scale factor $a(t)$ of the very early universe in this model has the time dependence $a(t{)}^2=a_0^2+t^2$. The violation of the strong energy condition of classical General Relativity to avoid the initial singularity requires that the central charge deficit of the theory be larger than a certain value. The significance of this solution is discussed.

RevTex, 10 pages, a new reference and related information is added

References in corpus (1)

• General Relativistic Energy Conditions: The Hubble expansion in the epoch of galaxy formation