Search for the Standard Model Higgs Boson in the Diphoton Decay Channel with $4.9{\mathrm{fb}}^{-1}$ of $pp$ Collision Data at $\sqrt{s}=7\mathrm{TeV}$ with ATLAS

A search for the standard model Higgs boson is performed in the diphoton decay channel. The data used correspond to an integrated luminosity of $4.9{\mathrm{fb}}^{-1}$ collected with the ATLAS detector at the Large Hadron Collider in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=7\mathrm{TeV}$. In the diphoton mass range 110–150 GeV, the largest excess with respect to the background-only hypothesis is observed at 126.5 GeV, with a local significance of 2.8 standard deviations. Taking the look-elsewhere effect into account in the range 110–150 GeV, this significance becomes 1.5 standard deviations. The standard model Higgs boson is excluded at 95% confidence level in the mass ranges of 113–115 GeV and 134.5–136 GeV.