We present a search for the standard model Higgs boson in final states with a charged lepton (electron or muon), missing transverse energy, and two or three jets, at least one of which is identified ...as a $b$-quark jet. The search is primarily sensitive to $WH\to\ell\nu b\bar{b}$ production and uses data corresponding to 9.7 fb$^{-1}$ of integrated luminosity collected with the D0 detector at the Fermilab Tevatron $p\bar{p}$ Collider at $\sqrt{s}=1.96$ TeV. We observe agreement between data and the expected background. For a Higgs boson mass of 125 GeV, we set a 95% C.L. upper limit on the production of a standard model Higgs boson of 5.2$\times\sigma_{\rm SM}$, where $\sigma_{\rm SM}$ is the standard model Higgs boson production cross section, while the expected limit is 4.7$\times\sigma_{\rm SM}$.
We present a search for the standard model Higgs boson in 9.5 fb-1 of ppbar collisions at sqrt(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 ppbar->ZH->vvbb production. The search is also sensitive to the WH->lvbb 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 sigma(ppbar->Z/WH), 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.
We present searches for the anomalous gamma WW and ZWW trilinear gauge boson couplings from WW and WZ production using lepton plus dijet final states and a combination with results from W gamma , WW, ...and WZ production with leptonic final states. The analyzed data correspond to up to 8.6 fb - 1 of integrated luminosity collected by the D0 detector in p p A= collisions at s = 1.96 TeV . We set the most stringent limits at a hadron collider to date assuming two different relations between the anomalous coupling parameters I kappa gamma , I>, and I g 1 Z for a cutoff energy scale I = 2 TeV . The combined 68% C.L. limits are - 0.057 < I kappa gamma < 0.154 , - 0.015 < 0.028 , and - 0.008 < I g 1 Z < 0.054 for the LEP parameterization, and - 0.007 < I kappa < 0.081 and - 0.017 < 0.028 for the equal couplings parameterization. We also present the most stringent limits of the W boson magnetic dipole and electric quadrupole moments.
We present a measurement of the average value of a new observable at hadron colliders that is sensitive to QCD dynamics and to the strong coupling constant, while being only weakly sensitive to ...parton distribution functions. The observable measures the angular correlations of jets and is defined as the number of neighboring jets above a given transverse momentum threshold which accompany a given jet within a given distance IR in the plane of rapidity and azimuthal angle. The ensemble average over all jets in an inclusive jet sample is measured and the results are presented as a function of transverse momentum of the inclusive jets, in different regions of IR and for different transverse momentum requirements for the neighboring jets. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector at the Fermilab Tevatron Collider in p p A= collisions at s = 1.96 TeV . The results are well described by a perturbative QCD calculation in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects. From these results, we extract the strong coupling and test the QCD predictions for its running over a range of momentum transfers of 50a400 GeV.
We present a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb(-1), collected by ...the D0 detector at a pp center-of-mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of R(-1)>260 GeV in a minimal UED model.
We present a search for the standard model Higgs boson in 9.5 fb-1 of p p A= 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 p p A= ? Z H ? ? ? A= b b A= production. The search is also sensitive to the W H ? l ? b b A= 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 s (p p A= ? 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.
We present the results of the combination of searches for the standard model Higgs boson produced in association with a W or Z boson and decaying into b bbar using the data sample collected with the ...D0 detector in p pbar collisions at sqrt{s}=1.96 TeV at the Fermilab Tevatron Collider. We derive 95% CL upper limits on the Higgs boson cross section relative to the standard model prediction in the mass range 100 GeV <= M_H <= 150 GeV, and we exclude Higgs bosons with masses smaller than 102 GeV at the 95% CL. In the mass range 120 GeV <= M_H <= 145 GeV the data exhibit an excess above the background prediction with a global significance of 1.5 standard deviations, consistent with the expectation in the presence of a standard model Higgs boson.
We present a search for Kaluza-Klein (KK) particles predicted by models with universal extra dimensions (UED) using a data set corresponding to an integrated luminosity of 7.3 fb$^{-1}$, collected by ...the D0 detector at a $p\bar p$ center of mass energy of 1.96 TeV. The decay chain of KK particles can lead to a final state with two muons of the same charge. This signature is used to set a lower limit on the compactification scale of $R^{-1}>260$ GeV in a minimal UED model.
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 measurement of the ratio of multijet cross sections in p (p) over barp collisions at root s = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set ...corresponding to an integrated luminosity of 0.7 fb(-1) collected with the DO detector. The ratio of the inclusive three-jet to two-jet cross sections, R-3/2, has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the PYriiiA event generator do not agree with the data, while SHERPA provides a reasonable description of the data. A perturbative QCD prediction in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects, gives a good description of the data.
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