Open string topological amplitudes and gaugino masses

We discuss the moduli-dependent couplings of the higher derivative F-terms (TrW 2 ) h−1 , where W is the gauge N = 1 chiral superfield. They are determined by the genus zero topological partition function F (0,h) , on a world-sheet with h boundaries. By string duality, these terms are also related to heterotic topological amplitudes studied in the past, with the topological twist applied only in the left-moving supersymmetric sector of the internal N = (2,0) superconformal field theory. The holomorphic anomaly of these couplings relates them to