Observation of an Excess of Events in the Search for the Standard Model Higgs boson with the ATLAS detector at the LHC

A preliminary combined search for the Standard Model Higgs boson with the ATLAS detector at the LHC is presented. The pp collisions datasets used correspond to integrated luminosities of 4.6 fb-1 to 4.9 fb-1 at $\sqrt{s}=7$ TeV in 2011 and 5.8 fb-1 to 5.9 fb-1 at $\sqrt{s}=8$ TeV in 2012. Searches for $H \to \gamma\gamma$, $H \to ZZ^{(*)}$, $H \to WW^{(*)}$, $H \to b\bar{b}$, and $H \to \tau^+\tau^-$ have been performed on the 2011 data, while only the $H \to \gamma\gamma$ and $H \to ZZ^{(*)}$ searches are improved compared to previous analyses and use both the 2011 and 2012 data. The Standard Model Higgs boson is excluded at the 95% confidence level for masses in the range 110 GeV to 122.6 GeV and 129.7 GeV to 558 GeV. An excess of events is observed for a Higgs boson mass hypothesis near 126.5 GeV. The local significance of this excess is 5.0$\sigma$, where the expected significance in the presence of a Standard Model Higgs boson for that mass hypothesis is 4.6$\sigma$.