Minimal subtraction formulation of massless fields for generic competing systems

We introduce the method of minimal subtraction in the computation of critical exponents of Lifshitz type generic competing systems using massless fields. We first treat the anisotropic cases, when several independent momentum scales define the renormalization group invariance of the scalar fields. In addition, we analyze the isotropic sector. We compute critical exponents using diagrammatic techniques at least up to two-loop level and show their equivalence with other methods presented in the literature.