Three-loop chiral effective potential in the Wess-Zumino model

We calculate the three-loop contribution to the chiral effective potential in the massless Wess-Zumino model. It is shown that while the non-renormalisation theorem forbids divergent contributions to the chiral potential, in the massless case the finite corrections survive. There are only three three-loop supergraphs that give rise to a superfield effective action in the pure chiral sector. Two of them are UV finite while the third requires one-loop counterterm corresponding to the chiral field renormalisation.