8,083 research outputs found

    Electroweak precision measurements with the CMS detector

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    We report on a precision measurement of the effective weak mixing angle using the forward-backward asymmetry of Drell-Yan (eeee and μμ\mu\mu) events in pp collisions at s=8 TeV\sqrt{s}=8~\mathrm{TeV} at CMS. The data sample corresponds to an integrated luminosity of 18.8 fb118.8~\mathrm{fb}^{-1} and 19.6 fb119.6~\mathrm{fb}^{-1} for muon and electron channels, respectively. The sample consists of 8.2 million dimuon and 4.9 million dielectron events. With new analysis techniques and large samples the statistical and systematic uncertainties are reduced by a factor of two compared to previous measurements at the LHC. The extracted value of the effective weak mixing angle from the combined eeee and μμ\mu\mu data samples is sin2θefflept=0.23101±0.00036(stat)±0.00018(syst)±0.00016(theory)±0.00030(pdf) sin^2\theta^{lept}_{eff}=0.23101\pm 0.00036(stat)\pm 0.00018(syst)\pm 0.00016(theory)\pm 0.00030(pdf) or sin2θefflept=0.23101±0.00052 sin^2\theta^{lept}_{eff}=0.23101\pm0.00052.Comment: 6 pages 2 figures. To be published in Proceeding of EPS 2017, Lido, Ital

    Standard Model Precision Electroweak Measurements at HL-LHC and Future Hadron Colliders

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    We investigate the uncertainties for current and future measurements of electroweak (EW) parameters at hadron colliders. These include the measurement of the mass of the top quark (MTM_T), the direct measurement of the mass of the W boson (MWdirectM_W^{direct}), the measurement of the effective EW mixing angle sin2θefflept\sin^2\theta^{\rm lept}_{\rm eff}(MZ_Z), and the measurement of the on-shell EW mixing angle sin2θW=1MW2/MZ2\sin^2\theta_{W}= 1- M_W^2/M_Z^2 which is equivalent to an indirect measurement of the W mass (MWindirectM_W^{indirect}). Reduction of a factor of 2 to 3 in the measurement errors is expected in the future.Comment: Talk presented CIPANP2015. 13 pages, LaTeX, 5 pdf figures,, 3 Table

    Studies of Higher Twist and Higher Order Effects in NLO and NNLO QCD Analysis of Lepton-Nucleon Scattering Data on F_2 and R =sigma_L/sigma_T

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    We report on the extraction of the higher twist contributions to F_2 and R = sigma_L/sigma_T from the global NLO and NNLO QCD fits to lepton nucleon scattering data over a wide range of Q^2. The NLO fits require both target mass and higher twist contributions at low Q^2. However, in the NNLO analysis, the data are described by the NNLO QCD predictions (with target mass corrections) without the need for any significant contributions from higher twist effects. An estimate of the difference between NLO and NNLO parton distribution functions is obtained.Comment: 5 pages, 6 figures, submitted to Eur. Phys.

    Modeling Neutrino and Electron Scattering Cross Sections in the Few GeV Region with Effective LOPDFsLO PDFs

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    We use new scaling variables xwx_w and ξw\xi_w, and add low Q2Q^2 modifications to GRV94 and GRV98 leading order parton distribution functions such that they can be used to model electron, muon and neutrino inelastic scattering cross sections (and also photoproduction) at both very low and high energie.Comment: 8 pages, 3 figures, Invited talk given by Arie Bodek at the X Mexican School of Particles and Fields, Playa del Carmen, Mexico, 200

    Modeling Neutrino Quasielastic Cross Sections on Nucleons and Nuclei

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    We calculate the total and differential quasielastic cross sections for neutrino and antineutrino scattering on nucleons using up to date fits to the nucleon elastic electromagnetic form factors GEpG_E^p, GEnG_E^n, GMpG_M^p, GMnG_M^n, and FAF_A and pseudoscalar form factors. We compare predictions of the cross sections for nucelons and nuclei to experimental data.Comment: 5 pages, 4 figures, Presented by Arie Bodek at CIPANP2003, New York City, NY 2003 - to be published in proceeding

    Extraction of the Axial Nucleon Form Factor from Neutrino Experiments on Deuterium

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    We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers (Q2Q^2), where the spatial structure of the nucleon is important, and use the Nachtman scaling variable ξ\xi to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high Q2Q^2 where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from \numu experiments on deuterium. We obtain an updated world average value from \numud, \numubarH and pion electroproduction experiments of MAM_{A} = 1.014±0.014GeV/c21.014 \pm 0.014 GeV/c^2. Our parameterizations are useful in modeling ν\nu interactions at low energies (e.g. for \numu oscillations experiments). The predictions for high Q2Q^2 can be tested in the next generation electron and \numu scattering experiments.Comment: Presented by A. Bodek at the European Physical Society Meeting, EPS2007, Manchester, England, July 2007, 4 pages, 2 figure