Measurement of the tZq cross section at 13 TeV with the CMS detector

TL;DR

This paper reports the first evidence for the production of a Z boson with a single top quark at 13 TeV, measuring the cross section and significance using CMS data from 2016.

Contribution

It provides the first measurement of the tZq production cross section at 13 TeV with CMS, including significance and detailed analysis of final states.

Findings

Measured cross section: 123^{+44}_{-39} fb

Observed significance: 3.7 standard deviations

Expected significance: 3.1 standard deviations

Abstract

Evidence is presented for standard model production of a Z boson in association with a single top quark. The analysis uses a data sample of proton-proton collisions at $\sqrt{s} = 13$ TeV recorded in 2016 by the CMS detector, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. Final states containing three leptons (electrons or muons) and at least two jets are investigated, and the measured cross section is $\sigma($pp $\rightarrow$ tZq $\rightarrow $Wb$\ell^{+}\ell^{-}$q) = 123$^{+44}_{-39}$ fb, where $\ell$ stands for electrons, muons or taus. The corresponding observed (expected) significance is 3.7 (3.1) standard deviations.