We investigate the presence of fractionally charged states in the massless sector of our superstring-derived standardlike model. We show that these states are divided into three classes. The states in two of these classes will receive a Planck mass, at the trilinear level of the superpotential, by giving a vacuum expectation value to a set of neutral singlets in the string model, while the states of the third class are exotic color triplets and are therefore confined and may become superheavy at the nonrenormalizable level of the superpotential.

• Received 21 October 1991

DOI:https://doi.org/10.1103/PhysRevD.46.3204