A lattice study of the Faddeev-Niemi effective action

We perform a lattice analysis of the Faddeev-Niemi effective action conjectured to describe the low energy sector of SU(2) Yang-Mills theory. We generalize the effective action such that it contains all operators built from a unit color vector field n with O(3)-symmetry and maximally four derivatives. To avoid the presence of Goldstone bosons, we include explicit symmetry breaking terms parametrized by an external field h of mass-dimension two. We find a mass gap of the order of 1.5 GeV.