Luminosity Monitoring in $pp$ collisions using $Z\rightarrow \ell \ell$ events at $\sqrt{s} = 13$ TeV with the ATLAS detector

The luminosity recorded by ATLAS can be monitored by measuring the production rate of the $Z$ boson by selecting events with two electrons or muons. The $Z$ production rate is corrected using trigger and reconstruction efficiencies determined from data, as well as a Monte Carlo correction for residual detector effects. The main motivations to pursue the $Z$-counting method are long term stability, in situ efficiency determination, independence from van der Meer scan calibration and robustness with respect to the mean number of inelastic $pp$ interactions per crossing (pileup) measured from Ref. [1]. This poster illustrates the basic principles of the method and shows the stability of $Z$-counting in comparison to the ATLAS-preferred luminosity values, primarily coming from the LUCID detector with corrections from other luminosity algorithms [1].