We report on a measurement of the inclusive jet cross section in $p \bar{p}$ collisions at a center-of-mass energy $\sqrt s=$1.96 TeV using data collected by the D0 experiment at the Fermilab ...Tevatron Collider corresponding to an integrated luminosity of 0.70 fb$^{-1}$. The data cover jet transverse momenta from 50 GeV to 600 GeV and jet rapidities in the range -2.4 to 2.4. Detailed studies of correlations between systematic uncertainties in transverse momentum and rapidity are presented, and the cross section measurements are found to be in good agreement with next-to-leading order QCD calculations.
From an analysis of the flavor-tagged decay \bsdec we obtain the width difference between the $B_s^0$ light and heavy mass eigenstates, $\Delta \Gamma_s \equiv \Gamma_L - \Gamma_H = 0.19 \pm 0.07 ...{\rm (stat)}\thinspace ^{+0.02}_{-0.01} {\rm (syst)}$ ps$^{-1}$, and the CP-violating phase, $\phi_{s} =-0.57 ^{+0.24}_{-0.30} {\rm (stat)}\thinspace ^{+0.07}_{-0.02} {\rm (syst)}$. The allowed 90% C.L. intervals of $\Delta \Gamma_s$ and $\phi_s$ are $0.06 <\Delta \Gamma_s <0.30$ ps$^{-1}$ and $-1.20 <\phi_s < 0.06$, respectively. The data sample corresponds to an integrated luminosity of 2.8 fb$^{-1}$ accumulated with the D0 detector at the Fermilab Tevatron collider.
We present a measurement of the forward-backward charge asymmetry ($A_{FB}$) in $p\bar{p} \to Z/\gamma^{*}+X \to e^+e^-+X$ events at a center-of-mass energy of 1.96 TeV using 1.1 fb$^{-1}$ of data ...collected with the D0 detector at the Fermilab Tevatron collider. $A_{FB}$ is measured as a function of the invariant mass of the electron-positron pair, and found to be consistent with the standard model prediction. We use the $A_{FB}$ measurement to extract the effective weak mixing angle $sin^2Theta^{eff}_W = 0.2327 \pm 0.0018 (stat.) \pm 0.0006 (syst.)$.
We present an observation for ZZ -> l+l-l'+l'- (l, l' = e or mu) production in ppbar collisions at a center-of-mass energy of sqrt(s) = 1.96 TeV. Using 1.7 fb-1 of data collected by the D0 experiment ...at the Fermilab Tevatron Collider, we observe three candidate events with an expected background of 0.14 +0.03 -0.02 events. The significance of this observation is 5.3 standard deviations. The combination of D0 results in this channel, as well as in ZZ -> l+l-nunubar, yields a significance of 5.7 standard deviations and a combined cross section of sigma(ZZ) = 1.60 +/- 0.63 (stat.) +0.16 -0.17 (syst.) pb.
Using 1 fb-1 of data from ppbar collisions at sqrt(s)=1.96 TeV at the Fermilab Tevatron collider collected by the D0 detector, we search for decays of Kaluza-Klein excitations of the graviton in the ...Randall-Sundrum model of extra dimensions to e+e- and diphotons. We set 95% confidence level upper limits on the production cross section times branching fraction which translate into lower limits on the mass of the lightest excitation between 300 and 900 GeV for values of the coupling k/M(Planck) between 0.01 and 0.1.
We present a study of four muon, four electron, and two muon two electron events using 1 fb^(-1) of data collected with the D0 detector at the Fermilab Tevatron p-barp Collider at sqrt(s) = 1.96 TeV. ...Requiring the lepton pair masses to be greater than 30 GeV, we observe one event, consistent with the expected background of 0.13 +- 0.03 events and with the predicted standard model ZZ and Z\gamma^* production of 1.71 +-0.15 events. We set an upper limit on the ZZ and Z\gamma^* cross section of 4.4 pb at the 95% C.L. We also derive limits on anomalous neutral trilinear ZZZ and ZZ\gamma^* gauge couplings. The one-parameter 95%$ C.L. coupling limits with a form factor scale Lambda = 1.2 TeV are -0.28 < f_(40)^Z < 0.28, -0.31 < f_(50)^Z < 0.29, -0.26 < f_(40)^\gamma < 0.26, and -0.30 < f_(5 0)^\gamma < 0.28.
We measure the ttbar production cross section in ppbar 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_ttbar=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.
We present a search for the production of neutral Higgs bosons phi decaying into tau+tau- final states in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an ...integrated luminosity of approximately 1 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. Limits on the production cross section times branching ratio are set. The results are interpreted in the minimal supersymmetric standard model yielding limits that are the most stringent to date at hadron colliders.
In 0.9 fb$^{-1}$ of $p \bar p$ collisions, D0 has observed an excess of events with an isolated lepton, missing transve rse momentum, and two to four jets. This excess is consistent with single top ...quark production. We examine these data to study the Lorentz structure of the $Wtb$ coupling. The standard model predicts a left-handed vector coupling at the $Wt b$ vertex. The most general lowest dimension, CP-conserving Lagrangian admits right-handed vector and left- or right-h anded tensor couplings as well. We find that the data prefer the left-handed vector coupling and set upper limits on the anomalous couplings. These are the first direct constraints on a general $Wtb$ interaction and the first direct limits on left- and right-handed tensor couplings.
We present a measurement of the electron charge asymmetry in ppbar->W+X->enu+X events at a center of mass energy of 1.96 TeV using 0.75 fb-1 of data collected with the D0 detector at the Fermilab ...Tevatron Collider. The asymmetry is measured as a function of the electron transverse momentum and pseudorapidity in the interval (-3.2, 3.2) and is compared with expectations from next-to-leading order calculations in perturbative quantum chromodynamics. These measurements will allow more accurate determinations of the proton parton distribution functions.
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