Combined search for the Standard Model Higgs boson using up to 4.9 fb-1 of pp collision data at sqrt(s) = 7 TeV with the ATLAS detector at the LHC

TL;DR

This paper reports a combined search for the Standard Model Higgs boson using ATLAS data from the LHC, observing an excess around 126 GeV with a local significance of 3.5 sigma, and excluding certain mass ranges at 95% confidence level.

Contribution

It presents the first combined analysis of multiple decay channels with up to 4.9 fb-1 of data, indicating a potential Higgs signal near 126 GeV and excluding several mass ranges.

Findings

Excess observed around 126 GeV with 3.5 sigma local significance.

Excluded Higgs mass ranges at 95% CL: 112.9-115.5 GeV, 131-238 GeV, 251-466 GeV.

Estimated global probability of background fluctuation: ~1.4%.

Abstract

A combined search for the Standard Model Higgs boson with the ATLAS experiment at the LHC using datasets corresponding to integrated luminosities from 1.04 fb-1 to 4.9 fb-1 of pp collisions collected at sqrt(s) = 7 TeV is presented. The Higgs boson mass ranges 112.9-115.5 GeV, 131-238 GeV and 251-466 GeV are excluded at the 95% confidence level (CL), while the range 124-519 GeV is expected to be excluded in the absence of a signal. An excess of events is observed around mH ~ 126 GeV with a local significance of 3.5 standard deviations (sigma). The local significance of H -> gamma gamma, H -> ZZ(*) -> lll'l' and H -> WW(*) -> lvl'v, the three most sensitive channels in this mass range, are 2.8 sigma, 2.1 sigma and 1.4 sigma, respectively. The global probability for the background to produce such a fluctuation anywhere in the explored Higgs boson mass range 110-600 GeV is estimated to be ~1.4% or, equivalently 2.2 sigma.