Filmer, E.K.Jackson, P.Kong, A.X.Y.Potti, H.Ruggeri, T.A.Ting, E.X.L.Çetin, Serkant Ali2024-05-192024-05-1920232470-0010https://doi.org/10.1103/PhysRevD.108.032012https://hdl.handle.net/20.500.12713/4515The production of a W boson in association with a single charm quark is studied using 140 fb - 1 of s = 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The charm quark is tagged by the presence of a charmed hadron reconstructed with a secondary-vertex fit. The W boson is reconstructed from the decay to either an electron or a muon and the missing transverse momentum present in the event. The charmed mesons reconstructed are D + ? K - ? + ? + and D * + ? D 0 ? + ? ( K - ? + ) ? + and the charge conjugate decays in the fiducial regions where p T ( e , ? ) > 30 GeV , | ? ( e , ? ) | < 2.5 , p T ( D ( * ) ) > 8 GeV , and | ? ( D ( * ) ) | < 2.2 . The integrated and normalized differential cross sections as a function of the pseudorapidity of the lepton from the W boson decay, and of the transverse momentum of the charmed hadron, are extracted from the data using a profile likelihood fit. The measured total fiducial cross sections are ? fid OS - SS ( W - + D + ) = 50.2 ± 0.2 ( stat ) - 2.3 + 2.4 ( syst ) pb , ? fid OS - SS ( W + + D - ) = 48.5 ± 0.2 ( stat ) - 2.2 + 2.3 ( syst ) pb , ? fid OS - SS ( W - + D * + ) = 51.1 ± 0.4 ( stat ) - 1.8 + 1.9 ( syst ) pb , and ? fid OS - SS ( W + + D * - ) = 50.0 ± 0.4 ( stat ) - 1.8 + 1.9 ( syst ) pb . Results are compared with the predictions of next-to-leading-order quantum chromodynamics calculations performed using state-of-the-art parton distribution functions. Additionally, the ratio of charm to anticharm production cross sections is studied to probe the s - s ¯ quark asymmetry. The ratio is found to be R c ± = 0.971 ± 0.006 ( stat ) ± 0.011 ( syst ) . The ratio and cross-section measurements are consistent with the predictions obtained with parton distribution function sets that have a symmetric s - s ¯ sea, indicating that any s - s ¯ asymmetry in the Bjorken- x region relevant for this measurement is small. © 2023 CERN, for the ATLAS Collaboration.eninfo:eu-repo/semantics/openAccessArticle10832-s2.0-8517374795210.1103/PhysRevD.108.032012Q1