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oai:recercat.cat:2445/1328752025-12-05T16:38:20Zcom_2072_1057col_2072_478823col_2072_478904col_2072_478917

00925njm 22002777a 4500 dc Badalov, Alexey author Calvo Gómez, Míriam author Casanova Mohr, Raimon author Garrido Beltrán, Lluís author Gascón Fora, David author Graciani Díaz, Ricardo author Graugés Pous, Eugeni author Marin Benito, Carla author Picatoste Olloqui, Eduardo author Rives Molina, Vicente José author Ruiz, Hugo (Ruiz Pérez) author Vilasis-Cardona, Xavier author LHCb Collaboration author 2019-05-09T09:51:53Z 2019-05-09T09:51:53Z 2015-07-28 2019-05-09T09:51:53Z The first observation of the B 0 s → η ′ η ′ decay is reported. The study is based on a sample of proton-proton collisions corresponding to 3.0     fb − 1 of integrated luminosity collected with the LHCb detector. The significance of the signal is 6.4 standard deviations. The branching fraction is measured to be [ 3.31 ± 0.64 ( stat ) ± 0.28 ( syst ) ± 0.12 ( norm ) ] × 10 − 5 , where the third uncertainty comes from the B ± → η ′ K ± branching fraction that is used as a normalization. In addition, the charge asymmetries of B ± → η ′ K ± and B ± → ϕ K ± , which are control channels, are measured to be ( − 0.2 ± 1.3 ) % and ( + 1.7 ± 1.3 ) % , respectively. All results are consistent with theoretical expectations. Física de partícules Experiments Particle physics Experiments Observation of the B0s→η′η′ Decay