Nonholomorphic corrections to the one-loop N=2 super Yang-Mills action

In addition to the familiar contribution from a holomorphic function F, the Kahler potential of the scalars in the nonabelian N = 2 vector multiplet receives contributions from a real function H. We determine the latter at the one-loop level, taking into account both supersymmetric matter and gauge loops, The function H characterizes the four-point coupling of the N = 2 vector multiplet vectors for constant values of their scalar superpartners. We discuss the consequences of our results.