242 research outputs found
Forward-backward asymmetry in top quark-antiquark production
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.84.112005
Direct measurement of the mass difference between top and antitop quarks
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.84.052005
Measurement of the W boson helicity in top quark decays using 5.4 fb^(−1) of pp-bar collision data
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.83.032009
Measurement of the WZ and ZZ production cross sections using leptonic final states in 8.6 fb(−1) of pp-bar collisions
This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.85.112005
Precise measurement of the top quark mass in the dilepton channel at D0
We measure the top quark mass (mt) in ppbar collisions at a center of mass
energy of 1.96 TeV using dilepton ttbar->W+bW-bbar->l+nubl-nubarbbar events,
where l denotes an electron, a muon, or a tau that decays leptonically. The
data correspond to an integrated luminosity of 5.4 fb-1 collected with the D0
detector at the Fermilab Tevatron Collider. We obtain mt = 174.0 +- 1.8(stat)
+- 2.4(syst) GeV, which is in agreement with the current world average mt =
173.3 +- 1.1 GeV. This is currently the most precise measurement of mt in the
dilepton channel.Comment: 7 pages, 4 figure
Direct measurement of the mass difference between top and antitop quarks
We present a direct measurement of the mass difference between top and
antitop quarks (dm) in lepton+jets top-antitop final states using the "matrix
element" method. The purity of the lepton+jets sample is enhanced for
top-antitop events by identifying at least one of the jet as originating from a
b quark. The analyzed data correspond to 3.6 fb-1 of proton-antiproton
collisions at 1.96 TeV acquired by D0 in Run II of the Fermilab Tevatron
Collider. The combination of the e+jets and mu+jets channels yields dm = 0.8
+/- 1.8 (stat) +/- 0.5 (syst) GeV, which is in agreement with the standard
model expectation of no mass difference.Comment: submitted to Phys. Rev.
Search for new fermions ("quirks") at the Fermilab Tevatron Collider
We report results of a search for particles with anomalously high ionization
in events with a high transverse energy jet and large missing transverse energy
in fb of integrated luminosity collected by the D0 experiment at
the Fermilab Tevatron collider. Production of such particles
(quirks) is expected in scenarios with extra QCD-like {\it SU(N)} sectors, and
this study is the first dedicated search for such signatures. We find no
evidence of a signal and set a lower mass limit of 107 ~GeV for the mass of a
charged quirk with strong dynamics scale in the range from 10 keV to
1 MeV.Comment: submitted to Phys. Rev. Letter
Measurements of differential cross sections of Z/gamma*+jets+X events in proton anti-proton collisions at sqrt{s}=1.96 TeV
We present cross section measurements for Z/gamma*+jets+X production,
differential in the transverse momenta of the three leading jets. The data
sample was collected with the D0 detector at the Fermilab Tevatron proton
anti-proton collider at a center-of-mass energy of 1.96 TeV and corresponds to
an integrated luminosity of 1 fb-1. Leading and next-to-leading order
perturbative QCD predictions are compared with the measurements, and agreement
is found within the theoretical and experimental uncertainties. We also make
comparisons with the predictions of four event generators. Two
parton-shower-based generators show significant shape and normalization
differences with respect to the data. In contrast, two generators combining
tree-level matrix elements with a parton shower give a reasonable description
of the the shapes observed in data, but the predicted normalizations show
significant differences with respect to the data, reflecting large scale
uncertainties. For specific choices of scales, the normalizations for either
generator can be made to agree with the measurements.Comment: Published in PLB. 11 pages, 3 figure
Search for the standard model and a fermiophobic Higgs boson in diphoton final states
We present a search for the standard model Higgs boson and a fermiophobic
Higgs boson in the diphoton final states based on 8.2 fb-1 of ppbar collisions
collected with the D0 detector at the Fermilab Tevatron Collider. No excess of
data above background predictions is observed and upper limits at the 95% C.L.
on the cross section multiplied by the branching fraction are set which are the
most restrictive to date. A fermiophobic Higgs boson with a mass below 112.9
GeV is excluded at the 95% C.L.Comment: 12 pages, 21 figures, submitted to PR
Search for first generation leptoquark pair production in the electron + missing energy + jets final state
We present a search for the pair production of first generation scalar
leptoquarks (LQ) in data corresponding to an integrated luminosity of 5.4
fb collected with the D0 detector at the Fermilab Tevatron Collider in
ppbar collisions at TeV. In the channel , where q, q' are u or d quarks, no significant excess
of data over background is observed, and we set a 95% C.L. lower limit of 326
GeV on the leptoquark mass, assuming equal probabilities of leptoquark decays
to eq and .Comment: 7 pages, 6 figures, submitted to PRD-R
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