LHC constraints on $W^\prime,~Z^\prime$ that couple mainly to third generation fermions

TL;DR

This paper uses collider data to constrain third-generation specific $W^\prime$ and $Z^\prime$ gauge bosons, finding weak limits on $W^\prime$ but strong constraints on $Z^\prime$, impacting explanations of certain anomalies.

Contribution

It provides the first detailed collider constraints on non-universal third-generation $W^\prime$ and $Z^\prime$ bosons, especially considering production mechanisms and their implications for anomalies.

Findings

Weak constraints on $W^\prime$ allow for explanations of $R(D^{(\star)})$ anomalies.

Strong constraints on $Z^\prime$ exclude significant sterile neutrino contributions to rare decays.

Constraints vary depending on production channels and decay modes.

Abstract

We use the results of CMS and ATLAS searches for resonances that decay to $\tau\nu$ or $tb$ and $\tau^+\tau^-$ or $t\bar t$ final states to constrain the parameters of non-universal $W^\prime$ and $Z^\prime$ gauge bosons that couple preferentially to the third generation. For the former we consider production from $c\bar{b}$ annihilation and find very weak constraints on the strength of the interaction and only for the mass range between 800 and 1100 GeV from the $pp \to \tau_h p_T^{\rm miss}$ channel. The constraints on the latter are much stronger and arise from both $t\bar t$ and $\tau^+\tau^-$ production. Treated separately, we find that the weak constraints on the $W^\prime$ still permit an explanation of the $R(D^{(\star)})$ anomalies with a light sterile neutrino whereas the stronger constraints on the $Z^\prime$ exclude significant light sterile neutrino contributions to the $K \to \pi \nu \bar\nu$ rates. Within specific models the masses of $W^\prime$ and $Z^\prime$ are of course related and we briefly discuss the consequences.