We study WW and WZ production with $l\nu q{q}$ ($l=e,\mu$) final states using data collected by the D0 detector at the Fermilab Tevatron Collider corresponding to 4.3 fb^-1 of integrated luminosity ...from p-pbar collisions at sqrt{s}=1.96 TeV. Assuming the ratio between the production cross sections $\sigma(WW)$ and $\sigma(WZ)$ as predicted by the standard model, we measure the total WV (V=W,Z) cross section to be $\sigma(WV)= 19.6^{+3.2}_{-3.0}$ pb, and reject the background-only hypothesis at a level of 7.9 standard deviations. We also use b-jet discrimination to separate the WZ component from the dominant WW component. Simultaneously fitting WW and WZ contributions, we measure $\sigma(WW) = 15.9^{+3.7}_{-3.2}$ pb and $\sigma(WZ) = 3.3^{+4.1}_{-3.3}$ pb, which is consistent with the standard model predictions.
We present a search for the production of neutral Higgs bosons decaying into tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated ...luminosity of 5.4 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the 95% C.L. on the production cross section multiplied by the branching ratio for a scalar resonance decaying into tautau pairs, and we then interpret these limits as limits on the production of Higgs bosons in the minimal supersymmetric standard model (MSSM) and as constraints in the MSSM parameter space.
We report results from searches for neutral Higgs bosons produced in p-pbar collisions recorded by the Dzero experiment at the Fermilab Tevatron Collider. We study the production of inclusive neutral ...Higgs boson in the tautau final state and in association with a b quark in the btautau and bbb final states. These results are combined to improve the sensitivity to the production of neutral Higgs bosons in the context of the minimal supersymmetric standard model (MSSM). The data are found to be consistent with expectation from background processes. Upper limits on MSSM Higgs boson production are set for Higgs boson masses ranging from 90 to 300 GeV. We exclude tanBeta>20-30 for Higgs boson masses below 180 GeV. These are the most stringent constraints on MSSM Higgs boson production in p-pbar collisions.
We report results from a search for neutral Higgs bosons produced in association with b quarks using data recorded by the D0 experiment at the Fermilab Tevatron Collider and corresponding to an ...integrated luminosity of 7.3 fb-1. This production mode can be enhanced in several extensions of the standard model (SM) such as in its minimal supersymmetric extension (MSSM) at high tanBeta. We search for Higgs bosons decaying to tau pairs with one tau decaying to a muon and neutrinos and the other to hadrons. The data are found to be consistent with SM expectations, and we set upper limits on the cross section times branching ratio in the Higgs boson mass range from 90 to 320 GeV/c2. We interpret our result in the MSSM parameter space, excluding tanBeta values down to 25 for Higgs boson masses below 170 GeV/c2.
We present a search for the standard model Higgs boson (H) in ppbar collisions at sqrt{s}=1.96 TeV in events containing a charged lepton (ell), missing transverse energy, and at least two jets, using ...5.4 fb^-1 of integrated luminosity recorded with the D0 detector at the Fermilab Tevatron Collider. This analysis is sensitive primarily to Higgs bosons produced through the fusion of two gluons or two electroweak bosons, with subsequent decay W->WW->ell+nu+q'qbar, where ell is an electron or muon. The search is also sensitive to contributions from other production channels, such as WH->ell+nu+bbbar In the absence of signal, we set limits at the 95% C.L. on the cross section for H production sigma(ppbar->H+X) in these final states. For a mass of MH=160 GeV, the limit is a factor of 3.9 larger than the cross section in the standard model, and consistent with expectation.
We present a measurement of the ttbar production cross section sigma(ttbar) in ppbar collisions at sqrt{s} = 1.96 TeV using 5.4 fb-1 of integrated luminosity collected with the D0 detector. We ...consider final states with at least two jets and two leptons (ee, emu, mumu), and events with one jet for the the emu final state as well. The measured cross section is sigma(ttbar)= 7.36 +0.90-0.79 (stat + syst) pb. This result combined with the cross section measurement in the lepton + jets final state yields sigma(ttbar)=7.56 +0.63-0.56 (stat + syst) pb, which agrees with the standard model expectation. The relative precision of 8% of this measurement is comparable to the latest theoretical calculations.
This report describes a search for associated production of W and Higgs bosons based on data corresponding to an integrated luminosity of L asymptotically = 5.3 fb super(-1) collected with the DO ...detector at the Fermilab Tevatron pp Collider. Events containing a W arrow right lnu candidate (with l corresponding to e or mu ) are selected in association with two or three reconstructed jets. One or two of the jets are required to be consistent with having evolved from a b quark. A multivariate discriminant technique is used to improve the separation of signal and backgrounds. Expected and observed upper limits are obtained for the product of the WH production cross section and branching ratios and reported in terms of ratios relative to the prediction of the standard model as a function of the mass of the Higgs boson (M sub(H)). The observed and expected 95% C.L. upper limits obtained for an assumed M sub(H) = 115 GeV are, respectively, factors of 4.5 and 4.8 larger than the value predicted by the standard model.
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