Slow expansion in the scalar-tensor theory of gravity

Abstract In this paper, we analyze the slow expansion scenario in the scalar-tensor theory of gravity. After considering the slow expansion solution H ≃ 0 , we discuss the slow expansion in the scalar-tensor theory by terms of the nearly scale-invariant primordial power spectrum and find that the primordial power spectrum can be determined by the coupling function f ( φ ) . After the slow expansion phase ends, general relativity can be recovered under certain conditions, and then the universe evolves in accordance with the standard cosmology. In the scalar-tensor theory, the slow expansion scenario provides a possible way to avoid the big bang singularity.