Ramond-Ramond couplings of noncommutative D-branes

We propose the leading couplings, in an alpha' expansion, of D-branes to Ra mond-Ramond (RR) potentials in a constant NS-NS B-field for an arbitrary ch oice of noncommutative parameter. The proposal is motivated by some string amplitude computations. The zero momentum couplings are topological in natu re and include Elliott's formula involving the noncommutative Chem characte r. The finite momentum couplings are given by smearing the zero momentum op erators along an open Wilson line. Comparisons between the RR couplings in different descriptions lead to a better understanding of the field redefini tions between gauge field variables (the Seiberg-Witten map) and help const rain alpha' corrections. In particular we recover the Seiberg-Witten map co njectured by one of the authors in hep-th/0011125. We also discuss the dyna mics of the transverse scalar fields and find evidence for a new derivative -driven dielectric effect. (C) 2001 Elsevier Science B.V. All rights reserv ed.