DOI: 10.17182/hepdata.83785.v1/t3
title: "Table 3" of "Observation of electroweak $W^{\pm}Z$ boson pair production in association with two jets in $pp$ collisions at $\sqrt{s} =$ 13 TeV with the ATLAS detector"

description: Numbers of observed and expected events in the $W^{\pm}Zjj$ signal region and in the three control regions, before the fit. The expected number of $WZjj-EW$ events from $SHERPA$ and the estimated number of background events from the other processes are shown. The sum of the background containing misidentified leptons is labelled "Misid. leptons". The total uncertainties are quoted.
description: CERN-LHC. An observation of electroweak $W^{\pm}Z$ production in association with two jets in proton-proton collisions is presented. 
The data collected by the ATLAS detector at the Large Hadron Collider in 2015 and 2016 at a centre-of-energy of $\sqrt{s}$ = 13TeV are used, corresponding to an integrated luminosity of 36.1 $fb^{-1}$. 
Events containing three identified leptons, either electrons or muons, and two jets are selected. 
The electroweak production of $W^{\pm}Z$ bosons in association with two jets is measured with an observed significance of 5.3 standard deviations. 
A fiducial cross section for electroweak production including interference effects is measured to be $\sigma_{WZjj-EW}$ = 0.57^{+0.14}_{-0.13} (stat.) ^{+0.07}_{-0.06} (syst.) fb. 
Differential cross section of $W^{\pm}Zjj$ production for several kinematic observables are also measured.

Fiducial phase space definition for the measurement:
- $p_{\mathrm{T}}$ of electrons and muons from Z0 decays &gt; 15 GeV
- $p_{\mathrm{T}}$ of electrons and muons from the $W^{\pm}$ decays &gt; 20 GeV
- $|\eta|$ of muons and electrons &lt; 2.5
- Leptons from the Z0 boson are separated by $\Delta R(\ell,\ell) &gt; 0.2$ from each other
- Leptons from the Z0 and W bosons are separated by $\Delta R(\ell,\ell) &gt; 0.3$ from each other
- |dilepton mass - Z0 mass| &lt; 10 GeV
- $m_{\mathrm{T}}$ of $W^{\pm}$ &gt; 30 GeV.
 
- at least 2 jets with opposite $|\eta|$. Jets are particle level jets with anti-kt R=0.4.
- $p_{\mathrm{T}}$ of the two jets &gt; 40 GeV
- $|\eta|$ of the two jets &lt; 4.5
- the first jet is chosen as the leading $p_{\mathrm{T}}$ jet
- the second jet is chosen among the remaining jets as the jet of highest $p_{\mathrm{T}}$ with $|\eta|$ opposite to the first jets
- invariant mass of the two jets &gt; 500 GeV
- leptons and jets separated by $\Delta R(\ell,jet) &gt; 0.3$
- processes with a b-quark in the initial state are excluded



At particle level, the kinematics of final-state prompt electrons and muons is computed including the contributions from
final-state radiated photons within a distance in the ($\eta,\phi$) plane of $\Delta R = \sqrt{(\Delta\eta)^2 + (\Delta\phi)^2} = 0.1$ around the direction of the charged lepton.
These dressed leptons and the final-state neutrinos that do not originate from hadron or $\tau$ decays are associated with the $W$ and $Z$ boson decay products with an
algorithmic approach, called ``resonant shape''.
This algorithm is based on the value of an estimator expressing
 the product of the nominal line shapes of the $W$ and $Z$ resonances

 $P = \left| \frac{1}{ m^2_{(\ell^+,\ell^-)} - \left(m_Z^{\textrm{PDG}}\right)^2 + i \; \Gamma_Z^{\textrm{PDG}} \; m_Z^{\textrm{PDG}} } \right|^2 \times \; \left| \frac {1} { m^2_{(\ell',\nu_{\ell'})} - \left(m_W^{\textrm{PDG}}\right)^2 + i \; \Gamma_W^{\textrm{PDG}} \; m_W^{\textrm{PDG}} } \right|^2$

where $m_Z^{\textrm{PDG}}$ ($m_W^{\textrm{PDG}}$) and $\Gamma_Z^{\textrm{PDG}}$ ($\Gamma_W^{\textrm{PDG}}$) are the world average mass and total width of the $Z$ ($W$) boson, respectively, as reported by the Particle Data Group \cite{Agashe:2014kda}.
The input to the estimator is the invariant mass $m$ of all possible pairs ($\ell^+,\ell^-$) and ($\ell',\nu_{\ell'}$)
satisfying the fiducial selection requirements defined in the next paragraph.
The final choice of which leptons are assigned to the $W$ or $Z$ bosons corresponds to the configuration exhibiting the highest value of the estimator.