Abstract
We present a search for the standard model Higgs boson in 9.5 fb−1 of pp¯ collisions at s=1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. The final state considered contains a pair of b jets and is characterized by an imbalance in transverse energy, as expected from pp¯→ZH→νν¯bb¯ production. The search is also sensitive to the WH→ℓνbb¯ channel when the charged lepton is not identified. The data are found to be in good agreement with the expected background. For a Higgs boson mass of 125 GeV, we set a limit at the 95% C.L. on the cross section σ(pp¯→[Z/W]H), assuming standard model branching fractions, that is a factor of 4.3 times larger than the theoretical standard model value, while the expected factor is 3.9. The search is also used to measure a combined WZ and ZZ production cross section that is a factor of 0.94±0.31(stat)±0.34(syst) times the standard model prediction of 4.4 pb, with an observed significance of 2.0 standard deviations.
Highlights
In the standard model (SM) [1], electroweak symmetry breaking is achieved via the introduction of a doublet of scalar fields, of which one degree of freedom remains once the W and Z vector bosons have acquired their masses
The final state considered contains a pair of b jets and is characterized by an imbalance in transverse energy, as expected from pp → ZH → ννbb production and decays
The data are found to be in good agreement with the expected background
Summary
In the standard model (SM) [1], electroweak symmetry breaking is achieved via the introduction of a doublet of scalar fields, of which one degree of freedom remains once the W and Z vector bosons have acquired their masses. A lower limit of 114.4 GeV was set on MH by the LEP Collaborations [8], while an upper limit at 127 GeV has been established by the ATLAS and CMS Collaborations [9, 10] These limits and those given below are all defined at the 95% C.L. The ATLAS and CMS Collaborations have published [9, 10] excesses above background expectations at approximately 125 GeV and have recently reported results confirming these excesses at the five standard deviations level [11, 12]. The distributions for the pre b-tag sample dijet ∆R and HT /HT (defined in Table III), and for the dijet invariant mass for medium b-tag and tight b-tag samples are shown in Fig. for the EW-control sample and in Fig. for the MJ-enriched sample
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