TOPOLOGICAL AMPLITUDES IN STRING THEORY

We show that certain type II string amplitudes at genus g are given by the topological partition function F(g) discussed recently by Bershadsky, Cecotti, Ooguri and Vafa. These amplitudes give rise to a term in the four-dimensional effective action of the form SIGMA(g) F(g)W2g, where W is the chiral superfield of N = 2 supergravitational multiplet. The holomorphic anomaly of F(g) is related to non-localities of the effective action due to the propaption of massless states. This result generalizes the holomorphic anomaly of the one loop case which is known to lead to non-harmonic gravitational couplings.