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oai:recercat.cat:20.500.14342/31562025-03-11T04:11:59Zcom_2072_482405com_2072_183628col_2072_482415

Study of the rare B0s and B0 decays into the π+ π− μ+ μ− final state Badalov, Alexey Calvo Gómez, Míriam Vilasís Cardona, Xavier LHCb Collaboration - CERN Universitat Ramon Llull. La Salle CERN Gran col·lisionador d'hadrons (França i Suïssa) Partícules (Física nuclear) Protons Col·lisions (Física nuclear) 539 A search for the rare decays B0s→π+π−μ+μ−and B0→π+π−μ+μ−is performed in a data set corresponding to an integrated luminosity of 3.0fb−1collected by the LHCb detector in proton–proton collisions at centre-of-mass energies of 7 and 8TeV. Decay candidates with pion pairs that have invariant mass in the range 0.5–1.3GeV/c2and with muon pairs that do not originate from a resonance are considered. The first observation of the decay B0s→π+π−μ+μ−and the first evidence of the decay B0→π+π−μ+μ−are obtained and the branching fractions, restricted to the dipion-mass range considered, are measured to be B(B0s→π+π−μ+μ−) =(8.6 ±1.5(stat) ±0.7(syst) ±0.7 (norm)) ×10−8and B(B0→π+π−μ+μ−) =(2.11±0.51(stat)±0.15(syst)±0.16(norm))×10−8, where the third uncertainty is due to the branching fraction of the decay B0→J/ψ(→μ+μ−)K∗(892)0(→K+π−), used as a normalisation. 2015-04-09 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion http://hdl.handle.net/20.500.14342/3156 https://doi.org/10.1016/j.physletb.2015.02.010 eng Physics Letters B , 2015, Vol. 743 (Abril) Attribution 4.0 International © CERN http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess 10 p. Elsevier