RT Journal Article T1 Study of the rare B0s and B0s decays into the π+π−μ+μ−final state A1 LHCb Collaboration, A1 Adeva Andany, Bernardo A1 Álvarez Cartelle, Paula A1 Dosil Suárez, Álvaro A1 Fernández Albor, Víctor Manuel A1 Gallas Torreira, Abraham Antonio A1 García Pardiñas, Julián A1 Hernando Morata, José Ángel A1 Plo Casasus, Máximo A1 Romero Vidal, Antonio A1 Saborido Silva, Juan José A1 Sanmartín Sedes, Brais A1 Santamarina Ríos, Cibrán A1 Vázquez Regueiro, Pablo A1 Vázquez Sierra, Carlos A1 Vieites Díaz, María AB 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. PB Elsevier SN 0370-2693 YR 2015 FD 2015 LK http://hdl.handle.net/10347/21938 UL http://hdl.handle.net/10347/21938 LA eng NO LHCb Collaboration et al. (2015). Study of the rare B0s and B0s decays into the π+π−μ+μ−final state. Physics Letters B, 743, 46-55 DS Minerva RD 24 abr 2026