First LHC constraints on anomalously interacting new vector bosons

TL;DR

This paper reports the first direct experimental constraints on hypothetical new vector bosons, $Z^*$ and $W^*$, using early LHC data, setting mass limits and demonstrating their unique signatures distinguishable from other heavy resonances.

Contribution

The study provides the first direct search results and exclusion limits for chiral $Z^*$ and $W^*$ bosons at the LHC, based on 7 TeV data with 40 pb$^{-1}$.

Findings

Excluded $Z^*$ mass below 1.15 TeV/c^2

Excluded $W^*$ mass below 1.35 TeV/c^2

First direct limits on $W^*$ and $Z^*$ production

Abstract

It was recently proposed to extend the Standard Model by means of new spin-1 chiral $Z^*$ and $W^{*\pm}$ bosons with the internal quantum numbers of the electroweak Higgs doublets. These bosons have unique signatures in transverse momentum, angular and pseudorapidity distributions of the final leptons, which allow one to distinguish them from other heavy resonances. With 40 pb$^{-1}$ of the LHC proton-proton data at the energy 7 TeV, the ATLAS detector was used to search for narrow resonances in the invariant mass spectrum of $e^+e^-$ and $\mu^+\mu^-$ final states and high-mass charged states decaying to a charged lepton and a neutrino. From the search exclusion mass limits of 1.15 TeV$/c^2$ and 1.35 TeV$/c^2$ were obtained for the chiral neutral $Z^*$ and charged $W^*$ bosons, respectively. These are the first direct limits on the $W^*$ and $Z^*$ boson production.