CONSTRAINTS FROM PRECISION ELECTROWEAK DATA ON LEPTOQUARKS AND BILEPTONS - ART. NO. 095013

Explicit expressions are derived for the oblique parameters S and T in certain extensions of the standard model. In particular, we consider leptoquarks and bileptons, and find phenomenological constraints on th eir allowed masses. Leptoquarks suggested by the neutral and charged c urrent anomalies at DESY HERA can give improved agreement with both S and T. If bileptons are the only new states, the singly charged one mu st be heavier than the directly established lower limit. Finally, we s tudy SU(15) grand unification and show that there are legions of param eter space where the theory is compatible with experimental data. [S05 56-2821(98)06719-8]