On Low-Energy Effective Action in N=2 Super Yang-Mills Theories on   Non-Abelian Background
  We compute the non-holomorphic corrections to low-energy effective action (higher derivative terms) in N=2, SU(2) SYM theory coupled to hypermultiplets on a non-abelian background for a class of gauge fixing conditions. A general procedure for calculating the gauge parameters depending contributions to one-loop superfield effective action is developed. The one-loop non-holomorphic effective potential is exactly found in terms of Euler dilogarithm function for specific choice of gauge parameters. 
A.T. Banin, I.L. Buchbinder, N.G. Pletnev