We have searched for second generation leptoquark (LQ) pairs in the \mu\mu+jets channel using 94+-5 pb^{-1} of pbar-p collider data collected by the D0 experiment at the Fermilab Tevatron during 1993-1996. No evidence for a signal is observed. These results are combined with those from the \mu\nu+jets and \nu\nu+jets channels to obtain 95% confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and $beta, the branching fraction of a LQ decay into a charged lepton and a quark. Lower limits of 200(180) GeV/c^2 for \beta=1(1/2) are set at the 95% C.L. on the mass of scalar LQ. Mass limits are also set on vector leptoquarks as a function of \beta.
No description provided.
This Letter describes a measurement of the muon cross section originating from b quark decay in the forward rapidity range 2.4 < y(mu) < 3.2 in pbarp collisions at sqrt(s) = 1.8 TeV. The data used in this analysis were collected by the D0 experiment at the Fermilab Tevatron. We find that NLO QCD calculations underestimate b quark production by a factor of four in the forward rapidity region. A cross section measurement using muon+jet data has been included in this version of the paper.
The forward muon cross section (per unit rapidity).
The cross section for muons originating from b-quark decay.
Integrated cross sections for muons originating from b-quark decay. The statistical and systematic errors are added in quadrature.
We present measurements of the b-bbar production cross section and angular correlations using the D0 detector at the Fermilab Tevatron p-pbar Collider operating at sqrt(s) = 1.8 TeV. The b quark production cross section for |y(b)|<1.0 and p_T(b)>6 GeV/c is extracted from single muon and dimuon data samples. The results agree in shape with the next-to-leading order QCD calculation of heavy flavor production but are greater than the central values of these predictions. The angular correlations between b and bbar quarks, measured from the azimuthal opening angle between their decay muons, also agree in shape with the next-to-leading order QCD prediction.
No description provided.
The errors are combinations of statistical and systematic uncertainties.
The distribution of MU+ MU- azimuthal angle difference.
This paper presents the first measurement of the inclusive J/Psi production cross section in the forward pseudorapidity region 2.5<|eta|<3.7 in ppbar collisions at sqrt(s)=1.8TeV. The results are based on 9.8 pb-1 of data collected using the D0 detector at the Fermilab Tevatron Collider. The inclusive J/Psi cross section for transverse momenta between 1 and 16 GeV/c is compared with theoretical models of charmonium production.
Only statistical errors are shown. Cross section tines branching ratio.
We report on a search for second generation leptoquarks (Phi_2) using a data sample corresponding to an integrated luminosity of 110 pb^{-1} collected at the Collider Detector at Fermilab. We present upper limits on the production cross section as a function of Phi_2 mass, assuming that the leptoquarks are produced in pairs and decay into a muon and a quark with branching ratio beta. Using a Next-to-Leading order QCD calculation, we extract a lower mass limit of M_{\Phi_2} > 202 (160) GeV$/c^{2} at 95% confidence level for scalar leptoquarks with beta=1(0.5).
Cross section times branching ratios.
We report on measurements of correlated\(b\bar b\) production in\(p\bar p\) collisions at\(\sqrt s = 630GeV\), using dimuon data to tag both theb and\(\bar b\) quarks. Starting from an inclusive dimuon sample we obtain improved cross-sections for single inclusive beauty production and confirm our earlier results on\(B^0 - \bar B^0\) mixing. From a study of\(b\bar b\) correlations we derive explicit cross-sections for semi-differential\(b\bar b\) production. We compare the measured cross-sections and correlations to\(\mathcal{O}\left( {\alpha _s^3 } \right)\) QCD predictions and find good quantitative agreement. From the measured angular distributions we establish a size-able contribution from higher order QCD processes with a significance of about seven standard deviations. A large nonperturbative contribution to these higher order corrections is excluded.
The first error is PT-dependent, and the second is PT-independent. Dimuons from different b-quarks.
The first error is PT-dependent, and the second is PT-independent. Dimuons from b chain decays (b --> c + mu, c --> mu).
Total cross-section for single b-quark production in the restricted rapidity range.
We have measured the production cross-section times branching ratio for J/ψ→μ + μ − in pp̄ interactions at √ s = 630 GeV in the kinematic range |y|<2.0 and p T >5 GeV /c, BR ( J /ψ→μ + μ − )σ( p p ̄ → J /ψ)=6.18±0.24±0.81 nb . The data sample collected in 1988 and 1989 for an integrated luminosity of 4.7 pb −1 represents a fivefold improvement over the statistics in our earlier study of the J / ψ production process, and the p T distribution which is measured extends to 28 GeV / c . Using event topology we show that the rate for the direct production of J / ψ , via radiative decays of χ states, is larger than that for production via B-hadrons. Production of ψ′ is also studied using the decay modes < ψ ′→ μ + μ − and ψ ′→ J / ψπ + ψ − .
Numerical values supplied by Nick Ellis.
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We report measurements of b-quark and B-hadron production in pp̄ collisions at √ s =630 GeV. We use muon samples to extract beauty production cross-sections over a wide range of transverse momentum in the central rapidity range | y | < 1.5. We compare our results to an O(α s 3 ) QCD prediction and find good agreement over the measured b-quark transverse momentum range 6 GeV / c to 54 GeV / c . Using the shape of the p T and y distribution predicted by QCD to extrapolate our data, we infer a total cross-section for b-quark production at √s=630 GeV of σ( p p ̄ → b b ̄ + X )=19.3±7( exp. )±9( th. μ b .
No description provided.
The cross section is multipled on the B(J/PSI --> MU+ MU-).
No description provided.
An extensive study of production and decay properties of charged and neutral Intermediate Vector Bosons (IVB) at the CERN proton-antiproton collider is presented. Intermediate Vector Bosons were detected in the electron, muon, and tau decay modes at centre-of-mass energies of 0.546 and 0.630 TeV. This paper is a summary, based on all the available data from the UA1 experiment from the running periods 1982–1985. Results are presented and compared with expectations of the Standard Eletroweak Model and QCD-improved Drell-Yan annihilation processes. The general conclusion is that there is an excellent agreement between the predictions of the Standard Model and our measurements.
No description provided.
No description provided.
No description provided.
We present a study of low mass dimuon events [ m ( μμ ) < 6 GeV/ c 2 ] from the UA1 experiment at the CERN p p collider. Contributions from semileptonic decays of heavy flavour particles, Drell-Yan type processes, J/ψ decays and leptonic decays of light mesons are extracted, and cross sections for high p T beauty and Drell-Yan production are derived. A limit for the branching fraction for the exotic decay B 0 →μ + μ − is also obtained. The cross section for section for low mass, high p T Drell-Yan prod uction is compared to the measured direct photon cross section using QED and QCD derived relationship. This relationship is used to infer a measurement of the single photon cross section at lower values of transverse momentum, where photons cannot be unambigously identified.
GLOBAL SYTEMATIC ERROR OF 30PCT HAS TO BE ADDED.