Flavour-changing neutral currents and leptophobic Z′ gauge bosons

Leptophobic Z' gauge bosons can appear in models with an E-6 gauge symmetry. We show that flavour-changing neutral currents can be generated in some of these models due to the mixing of the ordinary d(R), s(R) and b(R) quark fields with the exotic h(R). Because the Z' does not couple to charged leptons, the constraints on the flavour-changing couplings U-db(Z') and U-sb(Z') are relatively weak. Indeed, B-q(0)-(B) over bar (0)(q) mixing (q = d, s) can be dominated by Z' exchange, which will affect CP-violating rate asymmetries in B decays. Rare hadronic B decays can also be affected, while decays involving charged leptons will be unchanged. (C) 2002 Elsevier Science B.V. All rights reserved.