Abstract
Abstract A search for the Higgs boson produced in association with a W or Z boson in proton-proton collisions at a center-of-mass energy of 7 TeV is performed with the CMS detector at the LHC using the full 2011 data sample, from an integrated luminosity of 5 fb−1. Higgs boson decay modes to ττ and WW are explored by selecting events with three or four leptons in the final state. No excess above background expectations is observed, resulting in exclusion limits on the product of Higgs associated production cross section and decay branching fraction for Higgs boson masses between 110 and 200 GeV in these channels. Combining these results with other CMS associated production searches using the same dataset in the H→ γγ and H→ b $ \overline{\mathrm{b}} $ decay modes, the cross section for associated Higgs boson production 3.3 times the standard model expectation or larger is ruled out at the 95% confidence level for a Higgs boson mass of 125 GeV.
Highlights
Background estimationA combination of methods using data control samples and detailed studies with simulated events is used to estimate residual background contributions after selection
The analysis is sensitive to associated production where the Higgs boson decays into either a τ pair or W-boson pair
Upper limits of about 2.6–9 times greater than the predicted value are set at 95% CL for the product of the SM Higgs boson associated production cross section and decay branching fraction in the mass range 110 < mH < 200 GeV
Summary
Candidate signal events are recorded if they pass a trigger requiring the presence of a highpT electron pair, muon pair, or electron-muon pair. An isolation variable is constructed from the scalar sum of the transverse energy of all charged and neutral reconstructed particles contained within the cone, excluding the contribution from the lepton candidate itself. In the 3 channel, the dominant WZ → ν background is reduced by rejecting events with a same-flavor opposite-charge lepton pair with an invariant mass within 25 GeV of the Z-boson mass (mZ). The variable LT , defined as the scalar sum of the transverse energy of the three lepton candidates in the event, is required to be larger than 80 GeV This requirement is effective in rejecting some of the background coming from the semi-leptonic decays of heavy quarks, which has a softer pT spectrum. Events in the AP H → bb analysis are selected by requiring two jets identified as coming from b quarks and a vector boson candidate with high pT. The vector boson candidate can decay into one light lepton, two light leptons, or high ETmiss, corresponding to the W → ν, Z → , or Z → νν decay modes, respectively
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