Two-body $Z^{\prime }$ decays in the minimal 331 model

Abstract

The two-body decays of the extra neutral boson Z_2 predicted by the minimal 331 model are analyzed. At the three-level it can decay into standard model particles as well as exotic quarks and the new gauge bosons predicted by the model. The decays into a lepton pair are strongly suppressed, with $Br(Z_2-->l^{+}{l}^{-})10^{-2}$ and $Br(Z_2-->{\bar{\nu }}_l\nu )10^{-3}$. In the bosonic sector, Z_2 would decay mainly into a pair of bilepton gauge bosons, with a branching ratio below the 0.1 level. The Z_2 boson has thus a leptophobic and bileptophobic nature and it would decay dominantly into quark pairs. The anomaly-induced decays $Z_2-->Z_1\gamma$ and $Z_2-->Z_1{Z}_1$, which occurs at the one-loop level are studied. It is found that $Br(Z_2-->Z_1\gamma )10^{-9}$ and $Br(Z_2-->Z_1{Z}_1)10^{-6}$ at most. As for the $Z_2-->W^{+}{W}^{-}$ and $Z_2-->Z_{1}H$ decays, with H a relatively light Higgs boson, they are induced via Z'-Z mixing. It is obtained that $Br(Z_2-->W^{+}{W}^{-})10^{-2}$ and $Br(Z_2-->Z_{1}H)10^{-5}$. We also examine the flavor changing neutral current decays $Z_2-->tc$ and $Z_2-->tu$, which may have branching fractions as large as $10^{-3}$ and $10^{-5}$, respectively, and thus may be of phenomenological interest.

Comments: 14 pages, 3 figures, submitted to Physical Review D