Measurement of Properties of the Higgs Boson in Bosonic Decay Channels using the ATLAS Detector

Abstract

In the discovery of the Higgs boson, announced by ATLAS [1] and CMS [2] in July 2012, the analyses searching for bosonic decay channels played a crucial role among all channels accessible at the LHC. Since then, using two and a half times more data than was available for the discovery [3], more precise measurements of the properties of this particle have been achieved. Once again the H → ZZ∗ → 4`, H → γγ and H → WW ∗ → ``νν decay modes have proven to be fundamental in testing the agreement between the observed results and the Standard Model (SM) predictions. Thanks to several refinements achieved in both the H→ZZ∗→4` and H→γγ analyses, an improved measurement of the mass of the Higgs boson was recently published. The production modes and therefore the Higgs couplings were tested, and found to be in agreement with theory predictions. In addition, no significant deviations were found following new fiducial and differential cross section measurements, performed in both the H→ZZ∗→ 4` and H→ γγ decay channels. Furthermore, an indirect measurement of the Higgs width, ΓH , was made exploiting the H→ZZ∗ off-peak background interference effects. Finally, a combined measurement of the spin-CP properties of the boson is available. In the following sections the results obtained using approximately 25 fb−1 of pp collision data collected at 7 TeV and 8 TeV in 2011 and 2012 are reported. While in the H→ Zγ→ ``γ final state no signal has yet been observed, this channel will be particularly interesting in the coming years due to its sensitivity to the presence of new physics beyond the SM. The last section of this paper describes the analysis and the latest available results.