Measurements of the properties of the Higgs-like boson in the four lepton decay channel with the ATLAS detector using 25 fb$^{-1}$ of proton-proton collision data

We present an update of the search results and property measurements of the observed Higgs-like boson in the decay channel $H\to ZZ^{(*)}\to\ell^+\ell^-\ell^{+}\ell^{-}$ where $\ell$, $\ell'$ = $e$ or $\mu$, using proton-proton collision data corresponding to integrated luminosities of 4.6 $fb^{-1}$ and 20.7 $fb^{-1}$ at $\sqrt{s}=7$ TeV and $\sqrt{s}=8$ TeV, respectively, recorded with the ATLAS detector at the LHC. A clear excess of events over the background is observed at $m_H = 124.3$ GeV in the combined analysis of the two datasets with a significance of 6.6 standard deviations, corresponding to a background fluctuation probability of $2.7~\times~10^{-11}$. The mass of the Higgs-like boson is measured to be $124.3^{+0.6}_{-0.5}$(stat)$^{+0.5}_{-0.3}$(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 $1.7^{+0.5}_{-0.4}$. A study of Higgs boson production mechanisms allows a first measurement of couplings with this channel. A spin-parity analysis is performed.