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Albrecht, J.; Aslanides, E.; Barlow, R. J.; Ben-Haim, E.; Borghi, S.; Borgia, A.; Britsch, M.; Charles, M.; Cliff, H. V.; Cogoni, V.; Cook, A.; Counts, I.; Couturier, B.; Craik, D. C.; De Simone, P.; Dossett, D.; Dujany, G.; Dupertuis, F.; Dziurda, A.; Ekelhof, R.; Esen, S.; Evans, T.; Färber, C.; Frei, C.; Frosini, M.; Fu, J.; Gersabeck, M.; Ghez, Ph; Gianelle, A.; Göbel, C.; Gotti, C.; Granado Cardoso, L. A.; Graugés, E.; Hennessy, K.; Hicheur, A.; Jaeger, A.; Jaton, P.; Jawahery, A.; Karodia, S.; Kreps, M.; Kucewicz, W.; Kurek, K.; Leo, S.; Leverington, B.; Li, Y.; Liles, M.; Lopes, J. H.; Lopez-March, N.; Lupton, O.; Maciuc, F.; Malde, S.; Manca, G.; Mancinelli, G.; Mapelli, A.; Maratas, J.; Marks, J.; Martens, A.; Matev, R.; Matteuzzi, C.; Meier, F.; Merk, M.; Muheim, F.; Neubert, S.; Nguyen, A. D.; Nikodem, T.; O’Hanlon, D. P.; Obraztsov, V.; Orlandea, M.; Passaleva, G.; Patrignani, C.; Picatoste Olloqui, E.; Pilař, T.; Potterat, C.; Puig Navarro, A.; Rademacker, J. H.; Redi, F.; Robbe, P.; Rodrigues, E.; Romanovsky, V.; Ruf, T.; Sail, P.; Schmelling, M.; Schune, M.-H.; Smith, M.; Spradlin, P.; Sridharan, S.; Stahl, S.; Stoica, S.; Subbiah, V. K.; T’Jampens, S.; Thomas, E.; Tomassetti, L.; Vecchi, S.; Vesterinen, M.; Voong, D.; de Vries, J. A.; Wilkinson, G.; Xu, Z.; Zhang, L.; Zvyagin, A.
The European physical journal. C, Particles and fields, 07/2015, Letnik: 75, Številka: 7Journal Article
The production of the η c ( 1 S ) state in proton-proton collisions is probed via its decay to the p p ¯ final state with the LHCb detector, in the rapidity range 2.0 < y < 4.5 and in the meson transverse-momentum range p T > 6.5 GeV / c . The cross-section for prompt production of η c ( 1 S ) mesons relative to the prompt J / ψ cross-section is measured, for the first time, to be σ η c ( 1 S ) / σ J / ψ = 1.74 ± 0.29 ± 0.28 ± 0 . 18 B at a centre-of-mass energy s = 7 TeV using data corresponding to an integrated luminosity of 0.7 fb - 1 , and σ η c ( 1 S ) / σ J / ψ = 1.60 ± 0.29 ± 0.25 ± 0 . 17 B at s = 8 TeV using 2.0 fb - 1 . The uncertainties quoted are, in order, statistical, systematic, and that on the ratio of branching fractions of the η c ( 1 S ) and J / ψ decays to the p p ¯ final state. In addition, the inclusive branching fraction of b -hadron decays into η c ( 1 S ) mesons is measured, for the first time, to be B ( b → η c X ) = ( 4.88 ± 0.64 ± 0.29 ± 0 . 67 B ) × 10 - 3 , where the third uncertainty includes also the uncertainty on the J / ψ inclusive branching fraction from b -hadron decays. The difference between the J / ψ and η c ( 1 S ) meson masses is determined to be 114.7 ± 1.5 ± 0.1 MeV / c 2 .
