Fractionally Charged Particles and Supersymmetry Breaking in 4D Strings

Four-dimensional string theories predict in general the existence of light exotic particles with fractional electric charges. Such particles could escape present observations if they are confined by a gauge group of the "hidden" sector into integrally charged states. It is conceivable that the same gauge group is also responsible for dynamical supersymmetry breaking, via gaugino and scalar condensation. The communication of the breaking to the observable sector is now mediated by ordinary gauge interactions, implying that the confining scale can be in the TeV-region. We study the main phenomenological implications of this possibility. In particular, we analyze the pattern of supersymmetry breaking and the mass-spectrum of the sparticles. We also show that this scenario can be consistent with the unification of all coupling constants at the string scale.