Measuring $\mathrm WZ$ longitudinal polarization with the ATLAS detector

The prospects for measuring the spin density element, $\rho_{00}$, of the $\mathrm Z$ and $\mathrm W$ bosons in $\mathrm q\overline{\mathrm q} \rightarrow \mathrm WZ \rightarrow$ 4 leptons (muons and electrons) events in ATLAS is presented. This is done through reconstructing the decay angle of the leptons in the $\mathrm Z$ and $\mathrm W$ rest frames. The fraction of the longitudinal polarized $\mathrm Z$'s and $\mathrm W$'s are extracted from the angular distributions. The errors presented correspond to an integrated luminosity of a 100 $\rm{fb^{-1}}$. The expected final error on the measurement includes the systematic error due to detector correction and also due to the choice of proton parton distribution function.