Updated constraints on $Z'$ and $W'$ bosons decaying into bosonic and leptonic final states using the Run 2 ATLAS data

TL;DR

This paper uses the full ATLAS Run 2 data to set new, more stringent limits on the masses and mixing parameters of hypothetical $Z'$ and $W'$ bosons predicted by extended gauge models, covering masses from 1 to 6 TeV.

Contribution

It provides the most comprehensive and stringent constraints to date on $Z'$ and $W'$ bosons using the full Run 2 ATLAS dataset, extending previous limits significantly.

Findings

95% CL exclusion limits on $Z'$ masses up to 6 TeV.

New bounds on $Z$-$Z'$ mixing parameters.

Constraints on $W'$ boson masses and mixing parameters.

Abstract

The full ATLAS Run 2 data set with time-integrated luminosity of 139 fb$^{-1}$ in the diboson and dilepton channels is used to probe benchmark models with extended gauge sectors: the $E_6$-motivated Grand Unification models, the left-right symmetric $LR$ and the sequential standard model (EGM). These all predict neutral $Z'$ vector bosons, decaying into lepton pairs, $\ell\ell$, or into electroweak gauge boson pairs $WW$, where one $W$ in turn decays semileptonically. 95% C.L. exclusion limits on the $Z'$ resonance production cross section times branching ratio to electroweak gauge boson pairs and to lepton pairs in the mass range of $\sim$ 1 - 6 TeV are converted to constraints on the $Z$-$Z'$ mixing parameter and the heavy resonance mass. We present exclusion regions on the parameter space of the $Z'$ which are significantly extended compared to those obtained from the previous analyses performed with LHC data collected at 7 and 8 TeV in Run 1 as well as at 13 TeV in Run 2 at time-integrated luminosity of 36.1 fb$^{-1}$ and are the most stringent bounds to date. Also presented, from a similar analysis of electrically charged $W'$ bosons arising in the EGM, which can decay through $W'\to WZ$ and $W'\to \ell\nu$, are limits on the $W$-$W'$ mixing parameter and the charged $W'$ vector boson mass.