Noncritical anisotropic Bianchi type I string cosmology with α′ corrections

We present noncritical Bianchi type I string cosmology solutions in the presence of central charge deficit term Lambda. The leading-order string frame curvature appears to be in the high curvature limit R alpha ' greater than or similar to 1, which underlines the necessity of including higher-order alpha ' corrections. We give new solutions of two-loop (first-order alpha ') beta-function equations of the s model with nonzero Lambda and the dilaton field in both cases of the absence and presence of a spatially homogeneous H field (H = dB). Also, the evolution of solutions is studied in the Einstein frame, in which the string effective action can transform to Gauss-Bonnet gravity model coupled to a dilaton field with potential. We study explicit examples in first-order alpha ' with chosen values of appeared constants in the solutions and discuss the cosmological implications.