Measurement of the tt̄ production cross section in pp̄ collisions at s=1.96TeV
Physical Review Letters 100:19 (2008)
Abstract:
We measure the tt̄ production cross section in pp̄ collisions at s=1.96TeV in the lepton+jets channel. Two complementary methods discriminate between signal and background: b tagging and a kinematic likelihood discriminant. Based on 0.9fb-1 of data collected by the D0 detector at the Fermilab Tevatron Collider, we measure σtt̄=7.62±0.85pb, assuming the current world average mt=172.6GeV. We compare our cross section measurement with theory predictions to determine a value for the top-quark mass of 170±7GeV. © 2008 The American Physical Society.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 s=1.96TeV
Physical Review Letters 100:19 (2008)
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 σtt̄ in the lepton plus jets channel using 0.9fb-1 of pp̄ collision data at s=1.96TeV collected with the D0 detector. We extract R and σtt̄ by analyzing samples of events with 0, 1, and 2 identified b jets. We measure R=0.97-0.08+0.09(stat+syst) and σtt̄=8.18-0.84+0.90(stat+syst)±0.50(lumi)pb, in agreement with the standard model prediction. © 2008 The American Physical Society.Search for excited electrons in pp̄ collisions at s=1.96TeV
Physical Review D - Particles, Fields, Gravitation and Cosmology 77:9 (2008)
Abstract:
We present the results of a search for the production of an excited state of the electron, e*, in proton-antiproton collisions at s=1.96TeV. The data were collected with the D0 experiment at the Fermilab Tevatron Collider and correspond to an integrated luminosity of approximately 1fb-1. We search for e* in the process pp̄→e*e, with the e* subsequently decaying to an electron plus photon. No excess above the standard model background is observed. Interpreting our data in the context of a model that describes e* production by four-fermion contact interactions and e* decay via electroweak processes, we set 95% C.L. upper limits on the production cross section ranging from 8.9 to 27 fb, depending on the mass of the excited electron. Choosing the scale for contact interactions to be Λ=1TeV, excited electron masses below 756 GeV are excluded at the 95% C.L. © 2008 The American Physical Society.Measurement of the forward-backward charge asymmetry in top-quark pair production.
Phys Rev Lett 100:14 (2008) 142002
Abstract:
We present the first measurement of the integrated forward-backward charge asymmetry in top-quark-top-antiquark pair (tt) production in proton-antiproton (pp) collisions in the lepton+jets final state. Using a b-jet tagging algorithm and kinematic reconstruction assuming tt + X production and decay, a sample of 0.9 fb(-1) of data, collected by the D0 experiment at the Fermilab Tevatron Collider, is used to measure the asymmetry for different jet multiplicities. The result is also used to set upper limits on tt+X production via a Z' resonance.Measurement of the forward-backward charge asymmetry in top-quark pair production
Physical Review Letters 100:14 (2008)