Alfonso Albero, AlejandroBadalov, AlexeyCalvo Gómez, MíriamCamboni, AlessandroCoquereau, SamuelFernandez, G.Garrido Beltrán, LluísGascón Fora, DavidGraciani Díaz, RicardoGraugés Pous, EugeniMarin Benito, CarlaPicatoste Olloqui, EduardoVilasis-Cardona, XavierLHCb Collaboration2019-04-292019-04-292018-05-310031-9007https://hdl.handle.net/2445/132498A search for the rare decay Σ + → p μ + μ − is performed using p p collision data recorded by the LHCb experiment at center-of-mass energies √ s = 7 and 8 TeV, corresponding to an integrated luminosity of 3     fb − 1 . An excess of events is observed with respect to the background expectation, with a signal significance of 4.1 standard deviations. No significant structure is observed in the dimuon invariant mass distribution, in contrast with a previous result from the HyperCP experiment. The measured Σ + → p μ + μ − branching fraction is ( 2.2 + 1.8 − 1.3 ) × 10 − 8 , where statistical and systematic uncertainties are included, which is consistent with the standard model prediction.10 p.application/pdfengcc by (c) CERN; LHCb Collaboration, 2018http://creativecommons.org/licenses/by/3.0/es/Física de partículesExperimentsParticle physicsExperimentsinfo:eu-repo/semantics/article6846812019-04-29info:eu-repo/semantics/openAccess