A1/2, A1 and A0 are loop functions for fermions, vector bosons and scalars respectively, given as A1/2(x) = 2x2 x−1 + (x−1 − 1)f (x−1) , A1(x) = −x2 2x−2 + 3x−1 + 3(2x−1 − 1)f (x−1) , A0(x) = −x2 x−1 − f (x−1) ...