# 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

## TL;DR

This paper reports the first observation of electroweak WZ boson pair production with two jets at 13 TeV, confirming the Standard Model prediction with high significance and measuring related cross-sections.

## Contribution

It provides the first experimental observation of electroweak WZ production with two jets at the LHC and measures its cross-section with interference effects included.

## Key findings

- Electroweak WZ production observed with 5.3 sigma significance.
- Measured fiducial cross-section of 0.57 fb with uncertainties.
- Differential cross-sections for WZ+2 jets production are provided.

## Abstract

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-mass energy of $\sqrt{s} =$ 13 TeV 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 $\sigma_{WZjj\mathrm{-EW}} = 0.57 \; ^{+ 0.14} _{- 0.13} \,(\mathrm{stat.}) \; ^{+ 0.07} _{- 0.06} \,(\mathrm{syst.}) \; \mathrm{fb}$. Total and differential fiducial cross-sections of the sum of $W^\pm Z jj$ electroweak and strong productions for several kinematic observables are also measured.