Alfonso Albero, AlejandroCalvo Gómez, MíriamCamboni, AlessandroCoquereau, SamuelGarrido Beltrán, LluísGascón Fora, DavidGraciani Díaz, RicardoGraugés Pous, EugeniMarin Benito, CarlaLHCb Collaboration2022-05-042022-05-0420181126-6708https://hdl.handle.net/2445/185395A search for the lepton-flavour violating decays B0 s → e ±µ ∓ and B0 → e ±µ ∓ is performed based on a sample of proton-proton collision data corresponding to an integrated luminosity of 3 fb−1 , collected with the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The observed yields are consistent with the background-only hypothesis. Upper limits on the branching fraction of the B0 s → e ±µ ∓ decays are evaluated both in the hypotheses of an amplitude completely dominated by the heavy eigenstate and by the light eigenstate. The results are B(B0 s → e ±µ ∓) < 6.3 (5.4) × 10−9 and B(B0 s → e ±µ ∓) < 7.2 (6.0) × 10−9 at 95% (90%) confidence level, respectively. The upper limit on the branching fraction of the B0 → e ±µ ∓ decay is also evaluated, obtaining B(B0 → e ±µ ∓) < 1.3 (1.0) × 10−9 at 95% (90%) confidence level. These are the strongest limits on these decays to date20 p.application/pdfengcc-by (c) LHCb Collaboration (UB: Alfonso Albero, A. et al., 2018https://creativecommons.org/licenses/by/4.0/HadronsGran Col·lisionador d'HadronsFísica de partículesExperimentsHadronsLarge Hadron Collider (France and Switzerland)Particle physicsExperimentsinfo:eu-repo/semantics/article6847172022-05-04info:eu-repo/semantics/openAccess