MASSIVE HIDDEN MATTER AND GAUGING CONDENSATION

We formulate, in a duality-invariant way, the modification produced in the gaugino condensation mechanism by the presence of massive hidden matter (with masses higher than the condensation scale). This kind of scenario is, in fact, very common in string constructions. We observe that the same modification may also be obtained by renormalization group arguments when the effect due to the one-loop integration over heavy string modes is included. Comparison with the other possible scenario (masses smaller than the condensation scale) shows that a unified description for both cases is feasible. Then, we explore the phenomenological capabilities of such a scenario. They turn out to be much more promising than the ordinary ones, opening a way for obtaining a correct value of the dilaton (and thus of the gauge coupling constant) dynamically. We have also examined the connection between the effective lagrangian approach and the truncated superpotential approach for gaugino condensation, proving their equivalence in the physically relevant region.