We report the measurement of the one-dimensional charged kaon correlation functions using 600GeV/cΣ−, π− and 540GeV/cp beams from the SELEX (E781) experiment at the Fermilab Tevatron. K±K± ...correlation functions are studied for three transverse pair momentum, kT, ranges and parameterized by a Gaussian form. The emission source radii, R, and the correlation strength, λ, are extracted. The analysis shows a decrease of the source radii with increasing kaon transverse pair momentum for all beam types.
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.
The SELEX phototube RICH detector Engelfried, J.; Filimonov, I.; Kilmer, J. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/1999, Letnik:
431, Številka:
1
Journal Article
Recenzirano
Odprti dostop
In this article, construction, operation, and performance of the RICH detector of Fermilab experiment 781 (SELEX) are described. The detector utilizes a matrix of 2848 phototubes for the photocathode ...to detect Cherenkov photons generated in a
10
m
neon radiator. For the central region an
N
0 of
104
cm
−1
, corresponding to
13.6
hits
on a
β=1 ring, was obtained. The ring radius resolution measured is 1.6%.
We use higher-order quantum chromodynamics calculations to extract the mass of the top quark from the tt¯ cross section measured in the lepton + jets channel in pp¯ collisions at s=1.96 TeV using 5.3 ...fb−1 of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. The extracted top quark pole mass and MS¯ mass are compared to the current Tevatron average top quark mass obtained from direct measurements.
We present a measurement of the ratio of events with correlated t and t spins to the total number of tt events. This ratio f is evaluated using a matrix-element-based approach in 729 tt candidate ...events with a single lepton ℓ (electron or muon) and at least four jets. The analyzed pp collisions data correspond to an integrated luminosity of 5.3 fb-1 and were collected with the D0 detector at the Fermilab Tevatron collider operating at a center-of-mass energy \(\sqrt{s}=1.96\) TeV. Combining this result with a recent measurement of f in dileptonic final states, we find f in agreement with the standard model. In addition, the combination provides evidence for the presence of spin correlation in tt events with a significance of more than 3 standard deviations.
We present a search for charged Higgs bosons in top quark decays. We analyze the e+jets, μ+jets, ee, eμ, μμ, τe and τμ final states from top quark pair production events, using data from about 1 fb−1 ...of integrated luminosity recorded by the DØ experiment at the Fermilab Tevatron Collider. We consider different scenarios of possible charged Higgs boson decays, one where the charged Higgs boson decays purely hadronically into a charm and a strange quark, another where it decays into a τ lepton and a τ neutrino and a third one where both decays appear. We extract limits on the branching ratio B(t→H+b) for all these models. We use two methods, one where the tt¯ production cross section is fixed, and one where the cross section is fitted simultaneously with B(t→H+b). Based on the extracted limits, we exclude regions in the charged Higgs boson mass and tanβ parameter space for different scenarios of the minimal supersymmetric standard model.
We report on a measurement of the inclusive jet cross section in p (p) over bar collisions at a center-of-mass energy root 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 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.
We report the observation of the doubly strange b baryon Omega_b- in the decay channel Omega_b- to J/psi Omega-, with J/psi to mu+ mu- and Omega- to Lambda K-, in $p\bar{p}$ collisions at ...$\sqrt{s}=1.96$ TeV. Using approximately 1.3 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron Collider, we observe 17.8 +/- 4.9 (stat) +/- 0.8 (syst) Omega_b- signal events at a mass of 6.165 +/- 0.010 (stat) +/- 0.013(syst.) GeV. The significance of the observed signal is 5.4 sigma, corresponding to a probability of 6.7 x 10^{-8} of it arising from a background fluctuation.
We present a measurement of the tt¯ production cross section σtt¯ in pp¯ collisions at s=1.96 TeV using 5.4 fb−1 of integrated luminosity collected with the D0 detector. We consider final states with ...at least two jets and two leptons (ee, eμ, μμ), and events with one jet for the eμ final state as well. The measured cross section is σtt¯=7.36−0.79+0.90(stat+syst) pb. This result combined with the cross section measurement in the lepton+jets final state yields σtt¯=7.56−0.56+0.63(stat+syst) pb, which agrees with the standard model expectation. The relative precision of 8% of this measurement is comparable to the precision of the latest theoretical calculations.
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