Observation of B̄s0→J/ψf2′(1525) in J/ψK ⁺K ^- final states

The decay B̄s0→J/ψK ⁺K ^- is investigated using 0.16fb ^-1 of data collected with the LHCb detector using 7 TeV pp collisions. Although the J/ψ channel is well known, final states at higher K ⁺K ^- masses have not previously been studied. In the K ⁺K ^- mass spectrum we observe a significant signal in the f2′(1525) region as well as a nonresonant component. After subtracting the nonresonant component, we find B(B̄s0→J/ψf2′(1525))/ B(B̄s0→J/ψ)=(26.4±2.7±2.4)%.