This document presents a short update of the search results and a first measurement of the properties of the newly observed Higgs-like particle in the decay channel H → ZZ(∗) → l+l−l'+l'−, where l,l' = e or μ, using 4.6 fb−1 and 13 fb
−1 of proton-proton collisions at √s = 7 and √s = 8TeV, respectively, recorded with the ATLAS detector at the LHC. An excess of events over background is seen, with a minimum p0 value of 0.0021% (4.1 standard deviations) at mH = 123.5 GeV in the combined analysis of the two datasets. The fitted Higgs mass is measured to be mH = 123.5 ± 0.9 (stat.) ± 0.3 (syst.) GeV and the signal strength (the ratio of the observed cross-section to the expected SM cross-section) at this mass is found to be μ = 1.3+0.5−0.3. A spin-parity analysis is performed on the events with 115 GeV < mH < 130 GeV. The 0+ state is found to be favoured over the 0− and
2+ states with 0− excluded by 2.7 σ when compared to 0+
