One loop soft supersymmetry breaking terms in superstring effective theories

We perform a systematic analysis of soft supersymmetry breaking terms at th e one loop level in a large class of string effective field theories, This includes the so-called anomaly mediated contributions. We illustrate our re sults for several classes of orbifold models, In particular, we discuss a c lass of models where soft supersymmetry breaking terms are determined by qu asi model independent anomaly mediated contributions, with possibly non-van ishing scalar masses at the one loop level. We show that the latter contrib ution depends on the detailed prescription of the regularization process wh ich is assumed to represent the Planck scale physics of the underlying fund amental theory. The usual anomaly mediation case with vanishing scaler mass es at one loop is not found to be generic. However gaugino masses and A-ter ms always vanish at tree level if supersymmetry breaking is moduli dominate d with the moduli stabilized at self-dual points, whereas the vanishing of the B-term depends on the origin of the Ir-term in the underlying theory. W e also discuss the supersymmetric spectrum of O-I and O-II models, as well as a model of gaugino condensation. For reference, explicit spectra corresp onding to a Higgs mass of 114 GeV are given, Finally, we address general st rategies for distinguishing among these models. (C) 2001 Elsevier Science B .V. All rights reserved.