Alfonso Albero, AlejandroBadalov, AlexeyCalvo Gómez, MíriamCamboni, AlessandroCoquereau, SamuelFernandez, G.Garrido Beltrán, LluísGascón Fora, DavidGraciani Díaz, RicardoGraugés Pous, EugeniMarin Benito, CarlaPicatoste Olloqui, EduardoRives Molina, Vicente JoséVilasis-Cardona, XavierLHCb Collaboration2019-05-032019-05-032017-11-280031-9007https://hdl.handle.net/2445/132657The decays χc 1→J /ψ μ+μ- and χc 2→J /ψ μ+μ- are observed and used to study the resonance parameters of the χc 1 and χc 2 mesons. The masses of these states are measured to be m (χc 1)=3510.71 ±0.04 (stat ) ±0.09 (syst ) MeV and m (χc 2)=3556.10 ±0.06 (stat ) ±0.11 (syst ) MeV , where the knowledge of the momentum scale for charged particles dominates the systematic uncertainty. The momentum-scale uncertainties largely cancel in the mass difference m (χc 2)-m (χc 1)=45.39 ±0.07 (stat ) ±0.03 (syst ) MeV . The natural width of the χc 2 meson is measured to be Γ (χc 2)=2.10 ±0.20 (stat ) ±0.02 (syst ) MeV . These results are in good agreement with and have comparable precision to the current world averages.9 p.application/pdfengcc by (c) CERN; LHCb Collaboration, 2017http://creativecommons.org/licenses/by/3.0/es/Física de partículesExperimentsParticle physicsExperimentsinfo:eu-repo/semantics/article6780332019-05-03info:eu-repo/semantics/openAccess