Measurements of properties of the Higgs-like boson in the $H\rightarrow ZZ^{(*)} \rightarrow4\ell$ decay channel using the ATLAS detector

This article presents results on measurements of the signal strength, mass, and spin of the recently discovered Higgs-like boson in the $H\rightarrow ZZ^{(*)} \rightarrow 4\ell$ decay channel using the ATLAS detector. The results are based on the combined dataset of the 2011 and 2012 LHC runs consisting of $4.6 ~\rm{fb}^{-1}$ of $\sqrt{s} = 7$ TeV and $20.7 ~\rm{fb}^{-1}$ of $\sqrt{s} = 8$ TeV proton-proton collision data. An excess of events is observed corresponding to $m_{H} = 124.3$ GeV with a $p_{0}$ value of $2.7\times 10^{-11}$ (6.6 standard deviations). The fit at this mass point yields a signal strength relative to the SM of $1.7^{+0.5}_{-0.4}$ with $m_{H}=124.3^{+0.6}_{-0.5}$ (stat)$ ^{+0.5}_{-0.3}$ (syst) GeV. Tests of various spin-parity hypotheses are also presented, with the $0^{-}$ and $1^{+}$ hypotheses being excluded versus the $0^{+}$ hypothesis at > 97% confidence level.