Search for a W' boson decaying to a $\tau$ lepton and a neutrino in proton-proton collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a search for a W' boson decaying to a tau lepton and a neutrino using 13 TeV proton-proton collision data, setting new limits on W' boson masses and decay models.

Contribution

It presents the most stringent limits to date on W' boson masses and decay modes in proton-proton collisions at 13 TeV, using hadronic tau decays.

Findings

Excluded W' boson masses below 4.0 TeV at 95% CL in the sequential standard model.

Improved limits on W' bosons decaying preferentially to third-generation fermions.

Excluded heavy W' bosons with masses less than 1.7-3.9 TeV depending on the model.

Abstract

A search for a new high-mass resonance decaying to a tau lepton and a neutrino is reported. The analysis uses proton-proton collision data collected by the CMS experiment at the LHC at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The search utilizes hadronically decaying tau leptons. No excess in the event yield is observed at high transverse masses of the $\tau$ and missing transverse momentum. An interpretation of results within the sequential standard model excludes W' boson masses below 4.0 TeV at 95% confidence level. Existing limits are also improved on models in which the W' boson decays preferentially to fermions of the third generation. Heavy W' bosons with masses less than 1.7-3.9 TeV, depending on the coupling in the non-universal G(221) model, are excluded at 95% confidence level. These are the most stringent limits on this model to date.