CONFINEMENT OF FRACTIONAL CHARGES YIELDS INTEGER-CHARGED RELICS IN STRING MODELS

We demonstrate that all fractionally charged particles in the revamped flipped SU (5) model are confined by a hidden analogue of QCD. This result applies to states with mass ∼MP1 as well as to the lighter states discussed previously. We give sufficient conditions on other string models to confine light fractionally charged particles. The hidden sector of the revamped flipped SU (5) model contains metastable integer-charged hadron-like states. Such "cryptons" are likely to be generic features of string models that confine unwanted fractional charges, and should be present as dark matter in the Universe. © 1990.