Paper detail

Ramond-Ramond field strength couplings on D-branes

By examining in details the disk level S-matrix element of one massless RR and one NSNS states at order O(α'^2), we find the coupling of one RR and one NSNS fields on the world volume of a D$_p$-brane. The non-zero couplings involve the first derivative of the RR field strengths F^{(p)}, F^{(p+2)} and F^{(p+4)}. We then fix the on-shell ambiguity of the couplings by requiring consistency with the linear T-duality transformations. Moreover, consistency with the non-linear T-duality requires that the RR field strength in the above couplings to be {\cal F}=d{\cal C} where {\cal C}=e^{B}C.