Measurement of the production of a W boson in association with a charm quark in pp collisions at √s = 7TeV with the ATLAS detector

• Main Author: Santos, S. P. Amor dos
• Publication Date: 2014
• Other Authors: Carvalho, J., Fiolhais, M. C. N., Galhardo, B., Veloso, F., Wolters, H., ATLAS Collaboration
• Format: Article
• Language: eng
• Source: Repositórios Científicos de Acesso Aberto de Portugal (RCAAP)
• Download full: https://hdl.handle.net/10316/109477; https://doi.org/10.1007/JHEP05(2014)068
• topic: Electroweak interaction; Hadron-Hadron Scattering; Charm physics

The production of a W boson in association with a single charm quark is studied using 4.6 fb-1 of pp collision data at √s = 7TeV collected with the ATLAS detector at the Large Hadron Collider. In events in which a W boson decays to an electron or muon, the charm quark is tagged either by its semileptonic decay to a muon or by the presence of a charmed meson. The integrated and differential cross sections as a function of the pseudorapidity of the lepton from the W-boson decay are measured. Results are compared to the predictions of next-to-leading-order QCD calculations obtained from various parton distribution function parameterisations. The ratio of the strange-to-down sea-quark distributions is determined to be 0.96+ - 0 0.30 at Q2 = 1.9 GeV, which supports the hypothesis of an SU(3)-symmetric composition of the light-quark sea. Additionally the cross-section ratio σ(W+ + c)/σ(W- +c) is compared to the predictions obtained using parton distribution function parameterisations with different assumptions about the s–s quark asymmetry.