Badalov, AlexeyCalvo Gómez, MíriamCamboni, AlessandroGarrido Beltrán, LluísGascón Fora, DavidGraciani Díaz, RicardoGraugés Pous, EugeniMarin Benito, CarlaPicatoste Olloqui, EduardoRives Molina, Vicente JoséRuiz, Hugo (Ruiz Pérez)Vilasis-Cardona, XavierLHCb Collaboration2019-05-132019-05-132014-06-040031-9007https://hdl.handle.net/2445/133080Resonant structures in B 0 → ψ ′ π − K + decays are analyzed by performing a four-dimensional fit of the decay amplitude, using p p collision data corresponding to 3     fb − 1 collected with the LHCb detector. The data cannot be described with K + π − resonances alone, which is confirmed with a model-independent approach. A highly significant Z ( 4430 ) − → ψ ′ π − component is required, thus confirming the existence of this state. The observed evolution of the Z ( 4430 ) − amplitude with the ψ ′ π − mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin parity is determined unambiguously to be 1 + .9 p.application/pdfengcc by (c) CERN; LHCb Collaboration, 2014http://creativecommons.org/licenses/by/3.0/es/Física de partículesExperimentsParticle physicsExperimentsinfo:eu-repo/semantics/article6457602019-05-13info:eu-repo/semantics/openAccess