PERIODS, COUPLING-CONSTANTS AND MODULAR-FUNCTIONS IN N=2 SU(2) SYM WITH MASSIVE MATTER

We determine the mass dependence of the coupling constant for N = 2 SY M with N-f = 1, 2, 3 and 4 flavors. All these cases can be unified in one analytic expression, given by a Schwarzian triangle function. More over we work out the connection to modular functions which enables us to give explicit formulas for the periods. Using the form of the J-fun ctions we are able to determine in an elegant way the couplings and mo nodromies at the superconformal points.