Search for pair production of vector-like quarks in the bW$\overline{\mathrm{b}}$W channel from proton-proton collisions at $\sqrt{s} =$ 13 TeV

TL;DR

This paper reports a search for pair production of vector-like quarks T and Y in proton-proton collisions at 13 TeV, using CMS data, setting mass limits around 1.3 TeV due to no observed excess over the standard model.

Contribution

First search to set mass limits on vector-like T and Y quarks decaying to bW in the single lepton channel at 13 TeV.

Findings

No significant excess observed over the standard model.

Lower mass limit of 1295 GeV at 95% confidence level for T and Y quarks.

Analysis technique includes kinematic reconstruction for narrow mass peak detection.

Abstract

A search is presented for the production of vector-like quark pairs, T$\overline{\mathrm{T}}$ or Y$\overline{\mathrm{Y}}$, with electric charge of 2/3 (T) or -4/3 (Y), in proton-proton collisions at $\sqrt{s} =$ 13 TeV. The data were collected by the CMS experiment at the LHC in 2016 and correspond to an integrated luminosity of 35.8 fb$^{-1}$. The T and Y quarks are assumed to decay exclusively to a W boson and a b quark. The search is based on events with a single isolated electron or muon, large missing transverse momentum, and at least four jets with large transverse momenta. In the search, a kinematic reconstruction of the final state observables is performed, which would permit a signal to be detected as a narrow mass peak ($\approx$7% resolution). The observed number of events is consistent with the standard model prediction. Assuming strong pair production of the vector-like quarks and a 100% branching fraction to bW, a lower limit of 1295 GeV at 95% confidence level is set on the T and Y quark masses.