Calvo Gómez, MíriamCamboni, AlessandroComerma Montells, AlbertGarrido Beltrán, LluísGraciani Díaz, RicardoGraugés Pous, EugeniOyanguren Campos, Arantza dePérez-Calero Yzquierdo, AntonioPicatoste Olloqui, EduardoPotterat, CédricRives Molina, Vicente JoséRuiz, Hugo (Ruiz Pérez)Ruiz Valls, PabloVilasis-Cardona, XavierLHCb Collaboration2019-05-162019-05-162013-09-300031-9007https://hdl.handle.net/2445/133324A search for the lepton-flavor-violating decays B 0 s → e ± μ ∓ and B 0 → e ± μ ∓ is performed with a data sample, corresponding to an integrated luminosity of 1.0     fb − 1 of p p collisions at √ s = 7     TeV , collected by the LHCb experiment. The observed number of B 0 s → e ± μ ∓ and B 0 → e ± μ ∓ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B ( B 0 s → e ± μ ∓ ) < 1.1 ( 1.4 ) × 10 − 8 and B ( B 0 → e ± μ ∓ ) < 2.8 ( 3.7 ) × 10 − 9 at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, M LQ ( B 0 s → e ± μ ∓ ) > 101     TeV / c 2 and M LQ ( B 0 → e ± μ ∓ ) > 126     TeV / c 2 at 95% C.L., and are a factor of 2 higher than the previous bounds.9 p.application/pdfengcc by (c) CERN; LHCb Collaboration, 2013http://creativecommons.org/licenses/by/3.0/es/Física de partículesExperimentsParticle physicsExperimentsinfo:eu-repo/semantics/article6290352019-05-16info:eu-repo/semantics/openAccess