Alfonso Albero, AlejandroCalvo Gómez, MíriamCamboni, AlessandroCoquereau, SamuelGarrido Beltrán, LluísGascón Fora, DavidGironella Gironell, PereGolobardes, ElisabetGraciani Díaz, RicardoGraugés Pous, EugeniManera Escalero, R.Vázquez Gómez, RicardVilasis-Cardona, XavierCartelle, P. AlvarezLHCb Collaboration2021-03-102021-03-102020-07-312470-0010https://hdl.handle.net/2445/174857A measurement of the branching fraction of the decay B0s→K0SK0S is performed using proton-proton collision data corresponding to an integrated luminosity of 5  fb−1 collected by the LHCb experiment between 2011 and 2016. The branching fraction is determined to be B(B0s→K0SK0S)= [8.3±1.6(stat)±0.9(syst)±0.8(norm)±0.3(fs/fd)]×10−6, where the first uncertainty is statistical, the second is systematic, and the third and fourth are due to uncertainties on the branching fraction of the normalization mode B0→ϕK0S and the ratio of hadronization fractions fs/fd. This is the most precise measurement of this branching fraction to date. Furthermore, a measurement of the branching fraction of the decay B0→K0SK0S is performed relative to that of the B0s→K0SK0S channel, and is found to be B(B0→K0SK0S)B(B0s→K0SK0S)=[7.5±3.1(stat)±0.5(syst)±0.3(fs/fd)]×10−2.15 p.application/pdfengcc-by (c) Aaij, R. et al., 2020http://creativecommons.org/licenses/by/3.0/es/Gran Col·lisionador d'HadronsMesons (Física nuclear)BarionsLarge Hadron Collider (France and Switzerland)Mesons (Nuclear physics)Baryonsinfo:eu-repo/semantics/article7064782021-03-10info:eu-repo/semantics/openAccess