[Show abstract][Hide abstract] ABSTRACT: We search for resonant WW or WZ production using up to 5.4 fb-1 of integrated luminosity collected by the D0 experiment in Run II of the Fermilab Tevatron Collider. The data are consistent with the standard model background expectation, and we set limits on a resonance mass using the sequential standard model (SSM) W' boson and the Randall-Sundrum model graviton G as benchmarks. We exclude an SSM W' boson in the mass range 180 - 690 GeV and a Randall-Sundrum graviton in the range 300 - 754 GeV at 95% CL.
[Show abstract][Hide abstract] ABSTRACT: We present a measurement of the helicity of the W boson produced in top quark
decays using ttbar decays in the l+jets and dilepton final states selected from
a sample of 5.4 fb^-1 of collisions recorded using the D0 detector at the
Fermilab Tevatron ppbar collider. We measure the fractions of longitudinal and
right-handed W bosons to be f_0 = 0.669 +- 0.102 [ +- 0.078 (stat.) +- 0.065
(syst.)] and f_+ = 0.023 +- 0.053 [+- 0.041 (stat.) +- 0.034 (syst.)],
respectively. This result is consistent at the 98% level with the standard
model. A measurement with f_0 fixed to the value from the standard model yields
f_+ = 0.010 +- 0.037 [+- 0.022 (stat.) +- 0.030 (syst.) ].
[Show abstract][Hide abstract] ABSTRACT: We measure the charge asymmetry A ≡ (N++ - N--)/(N++ + N--) of like-sign dimuon events in 6.1 fb-1 of pp collisions recorded with the D0 detector at a center-of-mass energy square root(s) = 1.96 TeV at the Fermilab Tevatron collider. From A we extract the like-sign dimuon charge asymmetry in semileptonic b-hadron decays: A(sl)(b) = -0.009 57 ± 0.002 51(stat) ± 0.001 46(sys). It differs by 3.2 standard deviations from the standard model prediction A(sl)(b)(SM) = (-2.3(-0.6)(+0.5)) × 10(-4), and provides first evidence of anomalous CP violation in the mixing of neutral B mesons.
[Show abstract][Hide abstract] ABSTRACT: We have used a sample of γ+3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb-1 to determine the fraction of events with double parton scattering (fDP) in a single pp̅ collision at √s=1.96 TeV. The DP fraction and effective cross section (σeff), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in pT) jet transverse momentum pTjet2 within the range 15≤pTjet2≤30 GeV. In this range, fDP varies between 0.23≤fDP≤0.47, while σeff has the average value σeffave=16.4±0.3(stat)±2.3(syst) mb.
[Show abstract][Hide abstract] ABSTRACT: The data taken by Delphi at centre-of-mass energies between 189 and 209 GeV are used to place limits on the CP-conserving trilinear gauge boson couplings , λ γ and Δκ γ associated to W + W − and single W production at Lep2. Using data from the jj ℓ ν, jjjj, jjX and ℓ X final states, where j, ℓ and X represent a jet, a lepton and missing four-momentum, respectively, the following limits are set on the couplings when one parameter is allowed to vary and the others are set to their Standard Model values of zero: Results are also presented when two or three parameters are allowed to vary. All observations are consistent with the predictions of the Standard Model and supersede the previous results on these gauge coupling parameters published by Delphi.