Recent Higgs$\rightarrow$ZZ$^{(*)}\rightarrow$4l results with the ATLAS experiment

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\rightarrow ZZ^{(*)}\rightarrow l^{+}l^{-}l'^{+}l'^{-} $, where $l,l'=e$ or $mu$, using LEl and LTw of proton-proton collisions at EcmEl and EcmTw TeV, respectively, recorded with the ATLAS detector. An excess of events over background is seen, with a minimum $p_{0}$ value of 0.0021% (4.1 standard deviations) at $m_{H} = 123.5$ GeV in the combined analysis of the two datasets. The fitted Higgs mass is measured to be $m_{H} = 123.5 \pm 0.9$ (stat) $\pm 0.3$ (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 $\mu = 1.3^{+0.5}_{-0.3}$. A spin-parity analysis is performed on the events with 115 GeV $<$ $m_{H}$ $<$ 130 GeV. The $0^{+}$ state is found to be favoured over the $0^{-}$ and $2^{+}$ states with $0^{-}$ excluded by 2.7 $\sigma$ when compared to $0^{+}$.