An exact classical symmetry of effective field theories from superstrings and an anomalous source of observable supersymmetry breaking

The effective field theory suggested by the simplest superstring compactification has an exact classical nonlinear symmetry group that is likely to be present in a large class of realistic models obtained from superstrings. Certain group elements are closely related to duality transformations R→R-1 on the radius of compactification R. The symmetry is broken by chiral and conformal anomalies, which may provide the source of supersymmetry breaking in the observable sector. Modelling the effects of the anomalies using an effective composite supermultiplet for the strongly interacting hidden SUSY Yang-Mills sector, we find that a gaugino mass is generated with an order of magnitude that is very plausibly compatible with the requirements of phenomenology. (orig.)