NONPERTURBATIVE EFFECTIVE ACTIONS OF (N=2)-SUPERSYMMETRIC GAUGE-THEORIES

We elaborate on our previous work on (N 2)-supersymmetric Yang-Mills t heory In particular, we show how to explicitly determine the low energ y quantum effective action for G = SU(3) from the underlying hyperelli ptic Riemann surface, and calculate the leading instanton corrections. This is done by solving Picard-Fuchs equations and asymptotically eva luating period integrals. We find that the dynamics of the SU(3) theor y is governed by an Appell system of type F-4, and compute tile exact quantum gauge coupling explicitly in terms of Appell functions.