Measurement of the $t\bar{t}Z$ and $t\bar{t}W$ production cross sections in multilepton final states using 3.2 fb$^{-1}$ of $pp$ collisions at $\sqrt{s}$ = 13 TeV with the ATLAS detector

TL;DR

This paper reports measurements of the $tar{t}Z$ and $tar{t}W$ production cross sections in multilepton final states using 3.2 fb$^{-1}$ of 13 TeV proton-proton collision data from the ATLAS detector, confirming Standard Model predictions.

Contribution

First measurement of $tar{t}Z$ and $tar{t}W$ cross sections in multilepton channels at 13 TeV with ATLAS, using likelihood fits to extract results.

Findings

$\sigma_{tar{t}Z} = 0.9 extpm 0.3$ pb

$\sigma_{tar{t}W} = 1.5 extpm 0.8$ pb

Results agree with Standard Model predictions

Abstract

A measurement of the $t\bar{t}Z$ and $t\bar{t}W$ production cross sections in final states with either two same-charge muons, or three or four leptons (electrons or muons) is presented. The analysis uses a data sample of proton-proton collisions at $\sqrt{s} = 13$ TeV recorded with the ATLAS detector at the Large Hadron Collider in 2015, corresponding to a total integrated luminosity of 3.2 fb$^{-1}$. The inclusive cross sections are extracted using likelihood fits to signal and control regions, resulting in $\sigma_{t\bar{t}Z} = 0.9 \pm 0.3$ pb and $\sigma_{t\bar{t}W} = 1.5 \pm 0.8$ pb, in agreement with the Standard Model predictions.