Study of the decay Bs0→Ds(*)Ds(*)
Physical Review Letters 99:24 (2007)
Abstract:
We report a study of the decay Bs0→Ds(*)Ds(*) using a data sample corresponding to 1.3fb-1 of integrated luminosity collected by the D0 experiment in 2002-2006 during run II of the Fermilab Tevatron collider. One Ds(*) meson was partially reconstructed in the decay Ds→ μν, and the other Ds(*) meson was identified using the decay Ds→ π where no attempt was made to distinguish Ds and Ds* states. For the branching fraction Br(Bs0→Ds(*)Ds(*)) we obtain a 90% C.L. range [0.002,0.080] and central value 0.039-0.017+0.019(stat)-0.015+0.016(syst). This was subsequently used to make the most precise estimate of the width difference ΔΓsCP in the Bs0-B̄s0 system: ΔΓsCP/ Γs=0.079-0.035+0.038(stat)-0.030+0.031(syst). © 2007 The American Physical Society.Measurement of the tt̄ production cross section in pp̄ collisions at s=1.96TeV using kinematic characteristics of lepton+jets events
Physical Review D - Particles, Fields, Gravitation and Cosmology 76:9 (2007)
Abstract:
We present a measurement of the top quark pair production cross section in pp̄ collisions at s=1.96TeV utilizing 425pb-1 of data collected with the D0 detector at the Fermilab Tevatron Collider. We consider the final state of the top quark pair containing one high-pT electron or muon and at least four jets. We exploit specific kinematic features of tt̄ events to extract the cross section. For a top quark mass of 175 GeV, we measure σtt̄=6.4-1.2+1. 3(stat)±0.7(syst)±0.4(lum)pb, in good agreement with the standard model prediction. © 2007 The American Physical Society.Search for production of single top quarks via tcg and tug flavor-changing-neutral-current couplings.
Phys Rev Lett 99:19 (2007) 191802
Abstract:
We search for the production of single top quarks via flavor-changing-neutral-current couplings of a gluon to the top quark and a charm (c) or up (u) quark. We analyze 230 pb{-1} of lepton+jets data from pp[over] collisions at a center of mass energy of 1.96 TeV collected by the D0 detector at the Fermilab Tevatron Collider. We observe no significant deviation from standard model predictions, and hence set upper limits on the anomalous coupling parameters kappa{g}{c}/Lambda and kappa{g}{u}/Lambda, where kappa{g} define the strength of tcg and tug couplings, and Lambda defines the scale of new physics. The limits at 95% C.L. are kappa{g}{c}/Lambda<0.15 TeV-1 and kappa{g}{u}/Lambda<0.037 TeV-1.Search for a Higgs boson produced in association with a Z boson in p over(p, ̄) collisions
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 655:5-6 (2007) 209-216
Abstract:
We describe a search for the Standard Model Higgs boson with a mass of 105 GeV/ c2 to 145 GeV/ c2 in data corresponding to an integrated luminosity of approximately 450 pb-1 collected with the DØ detector at the Fermilab Tevatron p over(p, ̄) collider at a center-of-mass energy of 1.96 TeV. The Higgs boson is required to be produced in association with a Z boson, and the Z boson is required to decay to either electrons or muons with the Higgs boson decaying to a b over(b, ̄) pair. The data are well described by the expected background, leading to 95% confidence level cross section upper limits σ (p over(p, ̄) → Z H) × B (H → b over(b, ̄)) in the range of 3.1 pb to 4.4 pb. © 2007 Elsevier B.V. All rights reserved.Search for production of single top quarks via tcg and tug flavor-changing-neutral-current couplings
Physical Review Letters 99:19 (2007)