Simple non-Abelian extensions of the standard model gauge group and the diboson excesses at the LHC

Abstract

The ATLAS collaboration reported excesses at around 2 TeV in the di-boson production decaying into hadronic final states. We consider the possibility of explaining the excesses with extra gauge bosons in two simple non-Abelian extensions of the Standard Model. One is the so-called $G(221)$ models with a symmetry structure of $SU(2{)}_1\otimes SU(2{)}_2\otimes U(1{)}_X$ and the other is the $G(331)$ models with an extended symmetry of $SU(3{)}_C\otimes SU(3{)}_L\otimes U(1{)}_X$. The $W^{\prime }$ and $Z^{\prime }$ bosons emerge after the electroweak symmetry is spontaneously broken. Two patterns of symmetry breaking in the $G(221)$ models are considered in this work: one is $SU(2{)}_L\otimes SU(2{)}_2\otimes U(1{)}_X\to SU(2{)}_L\otimes U(1{)}_Y$, the other is $SU(2{)}_1\otimes SU(2{)}_2\otimes U(1{)}_Y\to SU(2{)}_L\otimes U(1{)}_Y$. The symmetry breaking of the $G(331)$ model is $SU(3{)}_L\otimes U(1{)}_X\to SU(2{)}_L\otimes U(1{)}_Y$. We perform a global analysis of $W^{\prime }$ and $Z^{\prime }$ phenomenology in ten new physics models, including all the channels of $W^{\prime }/Z^{\prime }$ decay. Our study shows that the leptonic mode and the dijet mode of $W^{\prime }/Z^{\prime }$ decays impose a very stringent bound on the parameter space in several new physics models. Such tight bounds provide a useful guide for building new physics models to address on the diboson anomalies. We also note that the Left-Right and Lepton-Phobic models can explain the $3.4\sigma$ $WZ$ excess if the $2.6\sigma$ deviation in the $W^{+}{W}^{-}$ pair around 2~TeV were confirmed to be a fluctuation of the SM backgrounds.

Comments: Publish version; title changed as suggested by journal Editor