Anisotropic homogeneous string cosmology with two-loop corrections

The two-loop (order alpha') beta-function equations, which are equivalent to the equations of motion of alpha'-corrected string effective action, are considered for anisotropic homogeneous space-times. These equations are solved for all Bianchi-type models in two schemes of effective action, namely R-2 and Gauss-Bonnet schemes with zero cosmological constant and then the metric, dilaton and B-field are found at alpha' perturbative corrections. (C) 2017 The Author(s). Published by Elsevier B.V.