Second order bosonic string effective action from O(d, d)

Abstract

The corrections to the tree-level effective action for the bosonic string up to second order in α^′ are fixed by requiring its dimensional reduction to 26 – d dimensions to be compatible with O(d, d) symmetry. The result is in agreement with the literature, but takes a simpler form than previously know expressions. We identify some structures in the Lagrangian which appear at least at the first three orders in α^′.