A note on the torsion dependence of D-brane RR couplings

The dependence on the torsion H = dh of the Wess-Zumino couplings of D-bran es that are trivially embedded in space-time is studied. We show that even in this simple set-up some torsion components can be turned on, with a non- trivial effect on the RR couplings. in the special cases in which either th e tangent or the normal bundle are trivial, the torsion dependence amounts to substitute the standard curvature with its generalization in the presenc e of torsion, in the usual couplings involving the roof genus (A) over cap. (C) 2001 Elsevier Science B.V. All rights reserved.