UC Irvine

Abstract: This paper presents a study of $$Z \rightarrow ll\gamma $$ Z → l l γ  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$$^{-1}$$ - 1 collected at a centre-of-mass energy $$\sqrt{s}$$ 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 $$Z \rightarrow ll\gamma \gamma $$ Z → l l γ γ  decays are also reported.