3RD-GENERATION LEPTOQUARK DECAYS AND COLLIDER SEARCHES

Collider searches for first-, second-, and third-generation scalar (S) or vector (V) leptoquarks (LQs) focus on the quark-lepton decay modes S,V --> ql. For SU(2)-doublet and -triplet leptoquarks with a suffici ently large splitting between the components, decays involving real W- boson emission (such as S-2((+5/3))-->S-2((+2/3)) W+ and others) becom e possible and can change the patterns of leptoquark decays. For third -generation leptoquarks, where these mass splittings might be large, s uch modes could dominate certain leptoquark decays as they are (if kin ematically allowed) guaranteed to be of order g(2) where g is the elec troweak coupling. We calculate the decay rates for all such processes involving SU(2)-doublet and triplet, scalar and vector leptoquarks. St andard limits on mass splittings from precision electroweak measuremen ts imply that only such decays involving SU(2)-doublet scalar LQs are likely kinematically possible. (C) 1997 Elsevier Science B.V.