Standard Model Higgs boson searches in the weak boson decay channels with the ATLAS detector

The search of the Standard Model Higgs boson decaying into a pair of weak bosons with the subsequent leptonic decay of the $W$ or $Z$ bosons is presented. The contributions achieved by this work range from the reevaluation of Higgs boson normalisation cross-sections, to the development of the analysis strategies using detailed Monte Carlo simulations and the search results for the $H \to ZZ \to l^{+}l^{-} \nu\bar{\nu}$, decay mode based on 4.7 fb$^{-1}$, of proton-proton collision data at $\sqrt{s}$ = 7 TeV taken during 2011 by the ATLAS detector. The computation of cross-sections values for Higgs boson production at centre-of-mass energies varying from 6 to 14 TeV, for the main production mechanisms at the LHC were documented for posterior usage among the Collaboration. Preliminary detector resolution studies on $Z \to\mu\mu$ events using early data collected by ATLAS are also described. Simulation studies for the $H \to ZZ^{(*)} \to l^{+}l^{-}l^{+}l^{-}$ and $H \to W^{+}W^{-} \to l^{+}\nu l^{-}\bar{\nu}$ channels included feasibility checks used to quantify the expected sensitivity of the analyses for various scenarios with different centre-of-mass energy, luminosity and detector calibration conditions. These results were part of the input that the Collaboration used to feed the schedule and plans of the LHC. On the $H \to ZZ \to l^{+}l^{-}\nu\bar{\nu}$ channel, upper limits on the Higgs boson production cross-section in a mass range between 200 and 900 GeV are set. With this channel by itself, the Standard Model Higgs boson particle is excluded at 95% confidence level in the mass range between 319 and 558 GeV. To complete the current picture of the Higgs boson searches in the ATLAS detector, a compilation of the different Higgs boson analyses performed by the ATLAS Collaboration are introduced. The Higgs boson existence is constrained to be in a narrow window between 122.5 GeV and 129 GeV with 95% confidence level; where an excess of 2.6 $\sigma$ local significance is observed.