Oscillatory Phase of Inflaton and Power-Law Expansion in Bianchi Type-I Universe

A homogeneous massive scalar field, minimally coupled to the spatially homogeneous and anisotropic background metric, in the semiclassical theory of gravity is examined. In the oscillatory phase of inflaton, the approximate leading solution to the semiclassical Einstein equation for the Bianchi type-I universe shows, each scale factor in each direction obeys t ^2/3 power-law expansion. Further noted that the evolution of scale factors are mutually correlated.