1,884,608 research outputs found

    Electroweak measurements from WW, ZZ and photon final states

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    We present the most recent precision electroweak measurements of single WW and ZZ boson cross section and properties from the LHC and Tevatron colliders, analyzing data collected by ATLAS, CDF, CMS, D0, and LHCb detectors. The results include the measurement of the single WW and ZZ boson cross section at LHC, the differential cross section measurements, the measurement of WW boson mass, the measurement of WW and ZZ charge asymmetry. These measurements provide precision tests on the electroweak theory, high order predictions and the information can be used to constraint parton distribution functions.Comment: 14 pages, 16 figures, PIC201

    Precision measurement and interpretation of inclusive W+, W- and Z/γ∗ production cross sections with the ATLAS detector

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    High-precision measurements by the ATLAS Collaboration are presented of inclusive W+→ℓ+ν, W-→ℓ-ν¯ and Z/γ∗→ℓℓ (ℓ=e,μ) Drell–Yan production cross sections at the LHC. The data were collected in proton–proton collisions at s=7TeV with an integrated luminosity of 4.6fb-1. Differential W+ and W- cross sections are measured in a lepton pseudorapidity range |ηℓ|<2.5. Differential Z/γ∗ cross sections are measured as a function of the absolute dilepton rapidity, for |yℓℓ|<3.6, for three intervals of dilepton mass, mℓℓ, extending from 46 to 150GeV. The integrated and differential electron- and muon-channel cross sections are combined and compared to theoretical predictions using recent sets of parton distribution functions. The data, together with the final inclusive e±p scattering cross-section data from H1 and ZEUS, are interpreted in a next-to-next-to-leading-order QCD analysis, and a new set of parton distribution functions, ATLAS-epWZ16, is obtained. The ratio of strange-to-light sea-quark densities in the proton is determined more accurately than in previous determinations based on collider data only, and is established to be close to unity in the sensitivity range of the data. A new measurement of the CKM matrix element |Vcs| is also provided

    Inclusive jet cross section measurement at D0

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    We present a new preliminary measurement of the inclusive jet cross section in pp-bar collisions based on a integrated luminosity of about 0.8 fb-1. The data were acquired using the D0 detector between 2002 and 2005. Jets are reconstructed using an iterative cone algorithm with radius R_cone = 0.7. The inclusive jet cross section is presented as a function of transverse jet momentum and rapidity. Predictions from perturbative QCD in next-to-leading order, plus threshold corrections in 2-loop accuracy describe the shape in the transverse jet momentum.Comment: 4 pages, 4 figures; proceedings of the DIS 2006 worksho

    Measurement of inclusive charged current interactions on carbon in a few-GeV neutrino beam

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    The SciBooNE Collaboration reports a measurement of inclusive charged current interactions of muon neutrinos on carbon with an average energy of 0.8 GeV using the Fermilab Booster Neutrino Beam. We compare our measurement with two neutrino interaction simulations: NEUT and NUANCE. The charged current interaction rates (product of flux and cross section) are extracted by fitting the muon kinematics, with a precision of 6-15% for the energy dependent and 3% for the energy integrated analyses. We also extract CC inclusive interaction cross sections from the observed rates, with a precision of 10-30% for the energy dependent and 8% for the energy integrated analyses. This is the first measurement of the CC inclusive cross section on carbon around 1 GeV. These results can be used to convert previous SciBooNE cross section ratio measurements to absolute cross section values.Comment: 21 pages, 16 figures. Accepted by Phys. Rev. D. Minor revisions to match the accepted versio

    The pp -> pp pi pi pi reaction channels in the threshold region

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    The cross section for prompt neutral and charged three pion production in pp interactions was measured at excess energies in the range 160 - 217 MeV. That comprises the first measurement of the pp->pp pi0pi0pi0 reaction and the comparison with the pp->pp pi+pi-pi0 reaction, in a very direct way. The experiment was performed above the eta meson production threshold and the cross section normalization was obtained from a concurrent measurement of the reaction pp->pp eta with the eta decaying into 3 pions. Since the same final states are selected, the measurement has a low systematical error. The measured cross section ratio sigma(pp->pp pi+pi-pi0)/sigma(pp->pp pi0\pi0\pi0) is compared to predictions of dominance of different isobars in the intermediate state.Comment: 12 pages, 4 figures New discussion on the pp->pp3pi reaction mechanis

    Measurement of Heavy Quark cross-sections at CDF

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    The measurement of heavy quark cross-sections provides important tests of the QCD theory. This paper reviews recent measurements of single b-quark and correlated b-quark cross-sections at CDF. Two new measurements of the single b-quark production at CDF agree with the first result from CDF Run II. This clarifies the experimental situation and confirms the recent agreement of theoretical prediction with data. A new measurement of the correlated bbˉb\bar{b} cross-section with dimuon events at CDF is presented. It agrees with theory and it does not confirm the anomalously large bbˉb\bar{b} cross-section seen in Run I by CDF and D{\not {\rm O}} in dimuon events.Comment: EPS HEP2007 conference held in Mancheste

    Chargino Production at LEP2 in a Supergravity Model

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    In the framework of a particular supergravity model which provides a natural solution to the μ\mu--problem we show how the discovery of a chargino at LEP2 and the measurement of its mass and production cross--section, together with the measurement of the mass of the lightest neutralino, would determine the entire Higgs and SUSY spectrum. We give detailed predictions for the Higgs and SUSY spectrum as a function of the chargino production cross--section, for constant values of the lightest chargino and gluino masses.Comment: 11 pages, latex, 4 figures uufile

    Longitudinal Analyses of the Effects of Trade Unions

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    This paper examines how measurement error biases longitudinal estimates of union effects. It develops numerical examples, statistical models, and econometric estimates which indicate that measurement error is a major problem in longitudinal data sets, so that longitudinal analyses do not provide the research panacea for determining the effects of unionism (or other economic forces) some have suggested. There are three major findings:1) The difference between the cross-section and longitudinal estimates is attributable in large part to random error in the measurement of who changes union status. Given modest errors of measurement, of the magnitudes observed,and a moderate proportion of workers changing union status, also of the magnitudes observed, measurement error biases downward estimated effects of unions by substantial amounts. 2) Longitudinal analysis of the effects of unionism on nonwage and wage outcomes tends to confirm the significant impact of unionism found in cross-section studies, with the longitudinal estimates of both nonwage and wage outcomes lover in the longitudinal analysis than in the cross-section analysis of the same data set. 3) The likely upward bias of cross-section estimates of the effect of unions and the likely downward bias of longitudinal estimates suggests that,under reasonable conditions, the two sets of estimates bound the "true" union impact posited in standard models of what unions do.

    Measurement of the cross section for the production of a W boson in association with b-jets in pp collisions at √s = 7 TeV with the ATLAS detector

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    A measurement is presented of the cross section for the production of a W boson with one or two jets, of which at least one must be a b-jet, in pp collisions at √s = 7 TeV. Production via top decay is not included in the signal definition. The measurement is based on 35 pb^(-1) of data collected with the ATLAS detector at the LHC. The W +b-jet cross section is defined for jets reconstructed with the anti-k_t clustering algorithm with transverse momentum above 25 GeV and rapidity within ±2.1. The b-jets are identified by reconstructing secondary vertices. The fiducial cross section is measured both for the electron and muon decay channel of the W boson and is found to be 10.2 ± 1.9(stat) ± 2.6(syst) pb for one lepton flavour. The results are compared with next-to-leading order QCD calculations, which predict a cross section smaller than, though consistent with, the measured value
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