Search for $W' \to t\bar{b}$ in the lepton plus jets final state in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 8 TeV with the ATLAS detector

TL;DR

This paper reports a search for new $W'$ bosons decaying into top and bottom quarks in proton-proton collisions at 8 TeV using the ATLAS detector, setting mass exclusion limits up to about 1.7-1.9 TeV.

Contribution

First search to set experimental limits on $W' o t\bar{b}$ decays at 8 TeV with a multivariate analysis approach.

Findings

No significant excess observed over Standard Model predictions.

Excluded $W'$ masses below 1.70 TeV for left-handed and 1.92 TeV for right-handed $W'$ bosons.

Set upper limits on cross-section times branching ratio as a function of $W'$ mass.

Abstract

A search for new charged massive gauge bosons, called $W'$, is performed with the ATLAS detector at the LHC, in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}$ = 8 TeV, using a dataset corresponding to an integrated luminosity of 20.3 fb$^{-1}$. This analysis searches for $W'$ bosons in the $W' \to t\bar{b}$ decay channel in final states with electrons or muons, using a multivariate method based on boosted decision trees. The search covers masses between 0.5 and 3.0 TeV, for right-handed or left-handed $W'$ bosons. No significant deviation from the Standard Model expectation is observed and limits are set on the $W' \to t\bar{b}$ cross-section times branching ratio and on the $W'$-boson effective couplings as a function of the $W'$-boson mass using the CL$_s$ procedure. For a left-handed (right-handed) $W'$ boson, masses below 1.70 (1.92) TeV are excluded at 95% confidence level.