that the field theory is no longer conformally invariant. We compute the quark-antiquark potential and show that its form is remarkably similar to that for a quark-antiquark pair in the ${\cal N}=4$ theory at finite temperature.

The masses of the quark flavors breaks the conformal invariance that is present in massless theory. In this case, the effective coupling does pick up a dependence on the energy scale as a result of instanton corrections. At high enough energies we expect these corrections can be neglected and the theory flows to the conformal field theory corresponding to the case of massless flavors. Indeed, the perturbative beta function still vanishes and the coupling goes to a constant at high energies. We will focus attention on the two and four derivative terms appearing in the low energy effective action. These terms are completely specified by a holomorphic prepotential ${\cal F}$ and a real function ${\cal H}$

$${S_{eff}={1\over 2i}\int d^{4}x\Big(\int d^{4}\theta{\cal F}(A)
-\int d^{4}\bar{\theta}\bar{{\cal F}}(\bar{A})\Big)+\int d^{4}x
\int d^{4}\theta d^{4}\bar{\theta}{\cal H}(A,\bar{A}).}$$

In what follows, we will only account for the one instanton corrections to both the prepotential and the four derivative terms. The prepotential does not receive any loop corrections for $N_f =4$. The one instanton 