Measurement of the tt[over] production cross section in pp[over] collisions at sqrt(s)=1.96 TeV.
Phys Rev Lett 100:19 (2008) 192004
Abstract:
We measure the tt[over] production cross section in pp[over] collisions at sqrt(s)=1.96 TeV in the lepton + jets channel. Two complementary methods discriminate between signal and background: b tagging and a kinematic likelihood discriminant. Based on 0.9 fb(-1) of data collected by the D0 detector at the Fermilab Tevatron Collider, we measure sigma(tt[over])=7.62+/-0.85 pb, assuming the current world average m(t)=172.6 GeV. We compare our cross section measurement with theory predictions to determine a value for the top-quark mass of 170+/-7 GeV.Simultaneous measurement of the ratio R=B(t --> Wb)/B(t --> Wq) and the top-quark pair production cross section with the D0 detector at sqrt(s) = 1.96 TeV.
Phys Rev Lett 100:19 (2008) 192003
Abstract:
We present the first simultaneous measurement of the ratio of branching fractions, R=B(t --> Wb)/B(t --> Wq), with q being a d, s, or b quark, and the top-quark pair production cross section sigma(tt[over]) in the lepton plus jets channel using 0.9 fb(-1) of pp[over] collision data at sqrt(s)=1.96 TeV collected with the D0 detector. We extract R and sigma(tt[over]) by analyzing samples of events with 0, 1, and > or =2 identified b jets. We measure R=0.97(+0.09)/(-0.08)(stat+syst) and sigma(tt[over])=8.18(+0.09)(-0.84)(stat+syst) +/- 0.50(lumi) pb, in agreement with the standard model prediction.Two-particle momentum correlations in jets produced in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 77:9 (2008)
Abstract:
We present the first measurement of two-particle momentum correlations in jets produced in pp̄ collisions at s=1.96TeV. Results are obtained for charged particles within a restricted cone with an opening angle of 0.5 radians around the jet axis and for events with dijet masses between 66 and 563GeV/c2. A comparison of the experimental data to theoretical predictions obtained for partons within the framework of resummed perturbative QCD in the next-to-leading log approximation shows that the parton momentum correlations survive the hadronization stage of jet fragmentation, giving further support to the hypothesis of local parton-hadron duality. The extracted value of the next-to-leading-log-approximation parton shower cutoff scale Qeff set equal to ΛQCD is found to be (1.4-0.7+0.9)×100MeV. © 2008 The American Physical Society.A combined search for the standard model Higgs boson at sqrt(s) = 1.96 TeV
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 663:1-2 (2008) 26-36
Abstract:
We present new results of the search for W H → ℓ ν b over(b, ̄) production in p over(p, ̄) collisions at a center-of-mass energy of sqrt(s) = 1.96 TeV, based on a dataset with integrated luminosity of 0.44 fb-1. We combine these new results with previously published searches by the D0 collaboration, for WH and ZH production analyzed in the E{combining long solidus overlay}T b over(b, ̄) final state, for ZH (→ ℓ+ ℓ- b over(b, ̄)) production, for WH (→ W W W) production, and for H (→ W W) direct production. No signal-like excess is observed either in the WH analysis or in the combination of all D0 Higgs boson analyses. We set 95% C.L. (expected) upper limits on σ (p over(p, ̄) → W H) × B (H → b over(b, ̄)) ranging from 1.6 (2.2) pb to 1.9 (3.3) pb for Higgs boson masses between 105 and 145 GeV, to be compared to the theoretical prediction of 0.13 pb for a Standard Model (SM) Higgs boson with mass mH = 115 GeV. After combination with the other D0 Higgs boson searches, we obtain for mH = 115 GeV an observed (expected) limit 8.5 (12.1) times higher than the SM predicted Higgs boson production cross section. For mH = 160 GeV, the corresponding observed (expected) ratio is 10.2 (9.0). © 2008 Elsevier B.V.Measurement of the tt̄ production cross section in pp̄ collisions at s=1.96TeV
Physical Review Letters 100:19 (2008)