Abstract
A search for a high-mass Higgs boson $H$ is performed in the $H\to{WW}\to\ell\nu\ell\nu$ and $H\to{WW}\to\ell\nu{qq}$ decay channels, using $pp$ collision data corresponding to an integrated luminosity of 20.3 fb$^{-1}$, collected at $\sqrt{s}=$ 8 TeV by the ATLAS detector at the Large Hadron Collider. No evidence of a high-mass Higgs boson is found. Limits on $\sigma_H\times \mathrm{BR}(H\to{WW})$ as a function of the Higgs boson mass $m_H$ are determined in three different scenarios: one in which the heavy Higgs boson has a narrow width compared to the experimental resolution, one a width increasing with the boson mass and modeled by the complex-pole scheme following the same behavior as in the Standard Model, and one for intermediate widths. The upper range of the search is $m_H=1500$ GeV for the narrow-width scenario and $m_H=1000$ GeV for the other two scenarios. The lower edge of the search range is $200-300$ GeV and depends on the analysis channel and search scenario. For each scenario, individual and combined limits from the two $WW$ decay channels are presented. At $m_H = 1500$ GeV, the highest mass point tested, $\sigma_H\cdot\mathrm{BR}(H\rightarrow WW)$ for a narrow-width Higgs boson is constrained to be less than 22 fb and 6.6 fb at the 95% CL for the gluon fusion and vector-boson fusion production modes, respectively.
Highlights
The boson discovered in 2012 by the ATLAS [1] and CMS [2] collaborations at the LHC matches the predictions for a Standard Model (SM) Higgs boson within the precision of current measurements [3, 4]
The background is expected to be dominated by W +jets production, with other important contributions from tt, single top, and multijet production that can be selected owing to the presence of leptons from heavy-flavour decays or jets misidentified as leptons
The search uses proton-proton collision data at a centre-of-mass energy of 8 TeV corresponding to an integrated luminosity of 20.3 fb−1
Summary
The boson discovered in 2012 by the ATLAS [1] and CMS [2] collaborations at the LHC matches the predictions for a Standard Model (SM) Higgs boson within the precision of current measurements [3, 4]. H → W W → ν ν and H → W W → νqq ( = e, μ) In these final states, ATLAS has previously reported the results of searches for heavy Higgs bosons using 4.7 fb−1 of data collected at a centre-of-mass energy of 7 TeV [11, 12]. This is referred to as the CPS scenario.
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