Darboux Coordinates and Instanton Corrections in Projective Superspace

By demanding consistency of the Legendre transform construction of hyperk\"ahler metrics in projective superspace, we derive the expression for the Darboux coordinates on the hyperk\"ahler manifold. We apply these results to study the Coulomb branch moduli space of 4D, N=2 super-Yang-Mills theory (SYM) on R^3 x S^1, recovering the results by GMN. We also apply this method to study the electric corrections to the moduli space of 5D, N=1 SYM on R^3 x T^2 and give the Darboux coordinates explicitly.