Measurements of \u03c8(2S) and X(3872) \u2192 J/\u03c8\u03c0+\u03c0\u2212 production in pp collisions at sqrt{s}=8 TeV with the ATLAS detector

Abstract

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 11.4 fb−1 of pp collisions at sqrt{s}=8 TeV by the ATLAS detector at the LHC. The ratio of cross-sections X(3872)/ψ(2S) is also given, separately for prompt and non-prompt 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 {R}_B=frac{mathrm{mathcal{B}}left(Bto X(3872)+mathrm{any}right)mathrm{mathcal{B}}left(X(3872)to J/psi {pi}^{+}{pi}^{-}right)}{mathrm{mathcal{B}}left(Bto psi (2S)+mathrm{any}right)mathrm{mathcal{B}}left(psi (2S)to J/psi {pi}^{+}{pi}^{-}right)}=left(3.95pm 0.32left(mathrm{s}mathrm{tat}right)pm 0.08left(mathrm{s}mathrm{y}mathrm{s}right)right)times {10}^{-2} 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)) > 10 GeV 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.