Observation of \({{\mathrm {B}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} \) and \({{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\uppi } ^+} {{\uppi } ^+} {{\uppi } ^-} \) decays

The decays \({{\mathrm {B}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} \) and \({{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\uppi } ^+} {{\uppi } ^+} {{\uppi } ^-} \) 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\(\mathrm {\,TeV}\). The branching fractions relative to that of \({{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\mathrm {K}} ^+} \) are measured to be $$\begin{aligned} \dfrac{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {{\mathrm {J}/\uppsi }} 3{{\uppi } ^+} 2{{\uppi } ^-} )}{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\mathrm {K}} ^+} )}= & {} ( 1.88\!\pm \! 0.17\!\pm \! 0.09)\!\times \! 10^{-2}, \\ \dfrac{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\uppi } ^+} {{\uppi } ^+} {{\uppi } ^-} )}{{\mathcal {B}} ( {{\mathrm {B}} ^+} \rightarrow {\uppsi {(2\mathrm {S})}} {{\mathrm {K}} ^+} )}= & {} ( 3.04\!\pm \!0.50\!\pm \!0.26)\!\times \! 10^{-2}, \end{aligned}$$ where the first uncertainties are statistical and the second are systematic.