  We construct modular invariants on the moduli space of quantum vacua of N=2
SYM with gauge group SU(2). We also introduce a nonchiral function K which is
expressed in terms of the Seiberg-Witten and Poincare' metrics. It turns out
that K has all the expected properties of the next to leading term in the
Wilsonian effective action whose modular properties are considered in the
framework of the dimensional regularization.
