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A Non-Singular Universe in String Cosmology

A. A. Al-Nowaiser·Murat Özer·M. O. Taha
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Abstract

We consider the low-energy effective string action in four dimensions including the leading order-$α'$ 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.

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A. A. Al-Nowaiser, Murat Özer, M. O. Taha. 1998-03-22. A Non-Singular Universe in String Cosmology. https://doi.org/10.1142/s0218271899000055

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