Study of $Z\to ll\gamma $ decays at $\sqrt{s}$ = 8 TeV with the ATLAS detector

This paper presents a study of $Z\to ll\gamma $ decays with the ATLAS detector at the Large Hadron Collider. The analysis uses a proton–proton data sample corresponding to an integrated luminosity of 20.2 fb ${}^{-1}$ collected at a centre-of-mass energy $\sqrt{s}$ = 8 TeV. Integrated fiducial cross-sections together with normalised differential fiducial cross-sections, sensitive to the kinematics of final-state QED radiation, are obtained. The results are found to be in agreement with state-of-the-art predictions for final-state QED radiation. First measurements of $Z\to ll\gamma \gamma $ decays are also reported.