Abstract
A search for the Standard Model Higgs boson has been performed in the H→WW→ℓνjj channel using 4.7 fb−1 of pp collision data recorded at a centre-of-mass energy of s=7 TeV with the ATLAS detector at the Large Hadron Collider. Higgs boson candidates produced in association with zero, one or two jets are included in the analysis to maximize the acceptance for both gluon fusion and weak boson fusion Higgs boson production processes. No significant excess of events is observed over the expected background and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 300 GeV<mH<600 GeV. The best sensitivity is reached for mH=400 GeV, where the observed (expected) 95% confidence level upper bound on the cross section for H→WW produced in association with zero or one jet is 2.2 pb (1.9 pb), corresponding to 1.9 (1.6) times the Standard Model prediction. In the Higgs boson plus two jets channel, which is more sensitive to the weak boson fusion process, the observed (expected) 95% confidence level upper bound on the cross section for H→WW production with mH=400 GeV is 0.7 pb (0.6 pb), corresponding to 7.9 (6.5) times the Standard Model prediction.
Highlights
In the Standard Model (SM), a scalar field with a non-zero vacuum expectation value breaks the electroweak symmetry, gives masses to the W /Z bosons and fermions [1,2,3,4,5,6], and manifests itself directly as a particle, the Higgs boson [2,3,5]
A primary goal of the Large Hadron Collider (LHC) is to test the SM mechanism of electroweak symmetry breaking by searching for Higgs boson production in high-energy proton–proton collisions
The ATLAS analysis excludes a Higgs boson with mass in the ranges 112.9–115.5 GeV, 131–238 GeV and 251–466 GeV while the CMS analysis excludes the range 127–600 GeV at 95% confidence level (CL)
Summary
In the Standard Model (SM), a scalar field with a non-zero vacuum expectation value breaks the electroweak symmetry, gives masses to the W /Z bosons and fermions [1,2,3,4,5,6], and manifests itself directly as a particle, the Higgs boson [2,3,5]. A primary goal of the Large Hadron Collider (LHC) is to test the SM mechanism of electroweak symmetry breaking by searching for Higgs boson production in high-energy proton–proton collisions. Results of Higgs boson searches in various channels using data up to an integrated luminosity of approximately 5 fb−1 have recently been reported by both the ATLAS and CMS Collaborations [7, 8]. The present search supersedes a previous analysis in the same Higgs boson decay channel published by the ATLAS Collaboration [11]. The distribution of the ν j j invariant mass m( ν j j), reconstructed using the ν invariant mass constraint m( ν) = m(W ) and the requirement that two of the jets in the event are consistent with a W → j j decay, is used to search for a Higgs boson signal. The best sensitivity to Higgs boson production in this analysis is expected for mH ∼ 400 GeV
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