Exact N = 2 Landau-Ginzburg flows

We find exactly solvable N=2 supersymmetric flows whose infrared fixed points are the N=2 minimal models. The exact S-matrices and the Casimir energy (a c-function) are determined along the entire renormalization-group trajectory. The c-functions run from c=3 (asymptotically) to N=2 minimal-model values, leading us to interpret these theories as the Landau-Ginzburg models with superpotential Xk+2. The calculation of the elliptic genus is consistent with this interpretation. We also find an integrable model in this hierarchy with spontaneously broken supersymmetry and superpotential X, and a series of integrable models with (0, 2) supersymmetry. The flows exhibit interesting behavior in the UV, including a relation to the N=2 super sine-Gordon model. We speculate about the relation between the kinetic term and the cigar target-space metric. (orig.)