On the Moduli Space of N = 2 Supersymmetric G_2 Gauge Theory
  We apply the method of confining phase superpotentials to N = 2 supersymmetric Yang-Mills theory with the exceptional gauge group G_2. Our findings are consistent with the spectral curve of the periodic Toda lattice, but do not agree with the hyperelliptic curve suggested previously in the literature. We also apply the method to theories with fundamental matter, treating both the example of SO(5) and G_2. 
Karl Landsteiner, John M. Pierre and Steven B. Giddings