One-loop effective potential of N=1 supersymmetric theory and decoupling effects

We study the decoupling effects in N = 1 (global) supersymmetric theories w ith chiral superfields at the one-loop level. Examples of gauge neutral chi ral superfields with minimal (renormalizable) as well as non-minimal (non-r enormalizable) couplings are considered, and decoupling in gauge theories w ith U(1) gauge superfields that couple to heavy chiral matter is studied. W e calculate the one-loop corrected effective Lagrangians that involve light fields and heavy fields with mass of order hi. Elimination of heavy fields by equations of motion leads to decoupling effects with terms that grow lo garithmically with M. These corrections renormalize light fields and coupli ngs in the theory (in accordance with the "decoupling theorem''). When the field theory is an effective theory of the underlying fundamental theory, l ike superstring theory, where the couplings are calculable, such decoupling effects modify the low energy predictions for the effective couplings of l ight fields. In particular, for the class of string vacua with an "anomalou s" U(1), the vacuum restabilization triggers decoupling effects, which can significantly modify the low energy predictions for couplings of the surviv ing light fields. We also demonstrate that quantum corrections to the chira l potential depending on massive background superfields and corresponding t o supergraphs with internal massless lines and external massive lines can a lso arise at the two-loop level. (C) 2000 Elsevier Science B.V. All rights reserved.