Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper reports a search for a hypothetical W' boson decaying into a top and bottom quark using 7 TeV proton-proton collision data, setting new limits on its mass and couplings.

Contribution

First LHC-based constraints on W' gauge couplings for various chiral scenarios, improving previous limits significantly.

Findings

Excluded W' masses below 1.85 TeV for right-handed couplings.

Placed constraints on W' gauge couplings for different chiral configurations.

Achieved the first constraints on W' couplings using LHC data.

Abstract

Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.