N = 2 super Yang-Mills low-energy effective action at two loops

We have carried out a two computation of the low-energy effective action for the four-dimensional N = 2 supersymmetric Yang-Mills system coupled to hypermultiplets, with the chiral superfields of the vector multiplet lying in an abelian subalgebra. We have found a complete cancellation at the level of the integrands of Feynman amplitudes, and therefore the two loop contribution to the action, effective or Wilson, is identically zero.