Amplitude Analysis and Branching Fraction Measurement of anti-B0s → J/ψ K+ K−

An amplitude analysis of the final state structure in the antiB0s → J/ψ K+ K− decay mode is performed using 1.0 fb^−1 of data collected by the LHCb experiment in 7 TeV center-of-mass energy pp collisions produced by the LHC. A modified Dalitz plot analysis of the final state is performed using both the invariant mass spectra and the decay angular distributions. Resonant structures are observed in the K+ K− mass spectrum as well as a significant nonresonant S-wave contribution over the entire K+ K− mass range. The largest resonant component is the ϕ(1020), accompanied by f0(980), f2′(1525), and four additional resonances. The overall branching fraction is measured to be B(antiB0s → J/ψ K+ K−) = (7.70 ± 0.08 ± 0.39 ± 0.60) x 10^−4, where the first uncertainty is statistical, the second systematic, and the third due to the ratio of the number of antiB0s to B− mesons produced. The mass and width of the f2′(1525) are measured to be 1522.2 ± 2.8_{−2.0}^{+5.3} MeV and 84 ± 6_{−5}^{+10} MeV, respectively. The final state fractions of the other resonant states are also reported