Search for the Standard Model Higgs boson in the diphoton decay channel with 4.9 fb-1 of pp collisions at sqrt(s) = 7 TeV with ATLAS

TL;DR

This paper reports a search for the Standard Model Higgs boson in the diphoton decay channel using 4.9 fb-1 of data from the ATLAS detector at 7 TeV, finding a modest excess near 126.5 GeV and excluding certain mass ranges.

Contribution

First search for the SM Higgs in diphoton channel with 4.9 fb-1 at 7 TeV, providing new limits and a potential signal around 126.5 GeV.

Findings

Observed excess at 126.5 GeV with 2.8 sigma local significance

Excluded Higgs mass ranges 113-115 GeV and 134.5-136 GeV at 95% CL

No definitive discovery due to significance levels

Abstract

A search for the Standard Model Higgs boson is performed in the diphoton decay channel. The data used corresponds to an integrated luminosity of 4.9 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 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.