Gauge singlet renormalisation in softly-broken supersymmetric theories

We consider the renormalisation of a softly-broken supersymmetric theory wi th singlet fields and a superpotential with a linear term. We show that the re exist exact beta -functions for both the linear term in the superpotenti al and the associated linear term in the Lagrangian. We also construct exac t renormalisation group invariant trajectories for these terms, correspondi ng to the conformal anomaly solution for the soft masses and couplings. (C) 2001 Published by Elsevier Science B.V.