Effective action of type II superstring theories at order α′3: NS-NS couplings

A bstract Recently, it has been shown that the minimum number of gauge invariant couplings for B -field, metric and dilaton at order α′ 3 is 872. These couplings, in a particular scheme, appear in 55 different structures. In this paper, up to an overall factor, we fix all parameters in type II supertirng theories by requiring the reduction of the couplings on a circle to be invariant under T-duality transformations. We find that there are 445 non-zero couplings which appear in 15 different structures. The couplings are fully consistent with the partial couplings that have been found in the literature by the four-point S-matrix element and by the non-linear Sigma model methods.