Measurements of psi(2S) and X(3872) -> J/psi pi (+) pi (-) production in pp collisions at root s=8 Tev with the ATLAS detector

Differential cross sections are presented for the prompt and non-prompt production of the hidden-charm states X(3872) and ψ(2S), in the decay mode J/ψπ+π−, measured using 11.4fb−1 of pp collisions at √s = 8TeV by the ATLAS detector at the LHC. The ratio of cross-sections X(3872)/ψ(2S) is also given, separately for prompt and nonprompt components, as well as the non-prompt fractions of X(3872) and ψ(2S). Assuming independent single effective lifetimes for non-prompt X(3872) and ψ(2S) production gives RB = B(B→X(3872) + any)B(X(3872)→J/ψπ+π−) B(B→ψ(2S) + any)B(ψ(2S)→J/ψπ+π−) = (3.95±0.32(stat)±0.08(sys))×10−2, while separating short- and long-lived contributions, assuming that the short-lived component is due to Bc decays, gives RB = (3.57 ± 0.33(stat) ± 0.11(sys)) × 10−2, with the fraction of non-prompt X(3872) produced via Bc decays for pT(X(3872)) > 10GeV being (25 ±13(stat) ± 2(sys) ± 5(spin))%. The distributions of the dipion invariant mass in the X(3872) and ψ(2S) decays are also measured and compared to theoretical predictions.