Observation of B⁺ → J/ψ3π⁺2π^- and B⁺ → ψ(2S)π⁺π⁺π^-

The decays B⁺ → J/ψ3π⁺2π^- and B⁺ → ψ(2S)π⁺π⁺π^- are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb^-1, collected by the LHCb experiment in proton-proton collisions at the centre-of-mass energies of 7 and 8 TeV. The branching fractions relative to that of B⁺ → J/ψ(2S)K⁺ are measured to be (B(B⁺→J/ψ3π⁺2π^-))/(B(B⁺→ψ(2S)K⁺)) = (1.88±0.17±0.09) x 10^-2, (B(B⁺→ψ(2S)π⁺π⁺π^-))/(B(B⁺→ψ(2S)K⁺)) = (3.04±0.50±0.26) x 10^-2, where the first uncertainties are statistical and the second are systematic. (orig.)