free global symmetry is The two $SU(N_f)$ factors act by unitary transformations on $Q$, $\tilde
Q$ respectively; baryon number assigns charge $+1(-1)$ to $Q$ ($\tilde
Q$), while under the $R$ symmetries the superspace coordinates $\theta_\alpha$ are assigned charge $1$, $Q$, $\tilde Q$ charge $B_f$, and $X$ charge $B_a$; anomaly freedom implies that: Without a superpotential this model is not currently understood beyond the vicinity of $N_f\simeq 2N_c$ where perturbative techniques are reliable \[\].

One of the main points of was that the theory simplifies if we add a superpotential This superpotential corresponds, for generic $k$, to a dangerously irrelevant perturbation of the theory with $W=0$ (see Appendix A), and thus cannot be ignored despite being irrelevant near the (free) UV fixed point of the theory. This superpotential has the effect of truncating the chiral ring of the theory, imposing the constraint which follows from the equation of motion for $X$; it also removes many of the flat directions of the original theory. In addition, the superpotential  breaks one of the two $R$ symmetries in . It is useful to think of $s_0$ (and other couplings to be introduced below) as background superfields whose lowest components get expectation values \[\]. The 