Abellan Beteta, CarlosCalvo Gómez, MíriamCamboni, AlessandroComerma Montells, AlbertOyanguren Campos, Arantza deGarrido Beltrán, LluísGraciani Díaz, RicardoGraugés Pous, EugeniLópez Asamar, EliasPérez-Calero Yzquierdo, AntonioPicatoste Olloqui, EduardoPotterat, CédricRives Molina, Vicente JoséRuiz, Hugo (Ruiz Pérez)Ruiz Valls, PabloVázquez Gómez, RicardVilasis-Cardona, XavierLHCb Collaboration2019-05-172019-05-172013-05-290031-9007https://hdl.handle.net/2445/133347The quantum numbers of the X ( 3872 ) meson are determined to be J P C = 1 ++ based on angular correlations in B + → X ( 3872 ) K + decays, where X ( 3872 ) → π + π − J / ψ and J / ψ → μ + μ − . The data correspond to 1.0     fb − 1 of p p collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements J P C = 2 − + is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X ( 3872 ) state.8 p.application/pdfengcc by (c) CERN; LHCb Collaboration, 2013http://creativecommons.org/licenses/by/3.0/es/Física de partículesExperimentsParticle physicsExperimentsinfo:eu-repo/semantics/article6289882019-05-17info:eu-repo/semantics/openAccess