Alfonso Albero, AlejandroGarcía Moreno, PaulaGarrido Beltrán, LluísGironella Gironell, P.Gomez Fernandez, S.Graugés Pous, EugeniLobo Salvia, A.Mauricio, J.Vazquez Gomez, R.Marin Benito, CarlaLHCb Collaboration2022-05-102022-05-1020211126-6708https://hdl.handle.net/2445/185496The decays Bs0 → J/ψπ+π−K+K− are studied using a data set corresponding to an integrated luminosity of 9 fb−1, collected with the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The decays Bs0 → J / ψK∗ 0K ¯ ∗ 0 and Bs0 → χc1(3872)K+K−, where the K+K−pair does not originate from a ϕ meson, are observed for the first time. Precise measurements of the ratios of branching fractions between intermediate χc1(3872)ϕ, J / ψK∗ 0K ¯ ∗ 0, ψ(2S)ϕ and χc1(3872)K+K− states are reported. A structure, denoted as X(4740), is observed in the J/ψϕ mass spectrum and, assuming a Breit-Wigner parameterisation, its mass and width are determined to be mX(4740)=4741±6±6MeV/c2,ΓX(4740)=53±15±11MeV, where the first uncertainty is statistical and the second is systematic. In addition, the most precise single measurement of the mass of the Bs0 meson is performed and gives a value of mBs0=5366.98±0.07±0.13MeV/c234 p.application/pdfengcc-by (c) Alfonso Albero, Alejandro et al., 2021https://creativecommons.org/licenses/by/4.0/HadronsGran Col·lisionador d'HadronsFísica de partículesExperimentsHadronsLarge Hadron Collider (France and Switzerland)Particle physicsExperimentsinfo:eu-repo/semantics/article7210842022-05-10info:eu-repo/semantics/openAccess