Observation of the B+ → Jψη′K+ decay

Abstract

The B+ → Jψη′K+ decay is observed for the first time using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb−1. The branching fraction of this decay is measured relative to the known branching fraction of the B+ → ψ(2S)K+ decay and found to be$$ \frac{\mathcal{B}\left({B}^{+}\to {J\psi \eta}^{\prime }{K}^{+}\right)}{\mathcal{B}\left({B}^{+}\to \psi (2S){K}^{+}\right)}=\left(4.91\pm 0.47\pm 0.29\pm 0.07\right)\times {10}^{-2}, $$ B B + → Jψη ′ K + B B + → ψ 2 S K + = 4.91 ± 0.47 ± 0.29 ± 0.07 × 10 − 2 , where the first uncertainty is statistical, the second is systematic and the third is related to external branching fractions. A first look at the J/ψη′ mass distribution is performed and no signal of intermediate resonances is observed.