Observation of X(3872) production in pp collisions at √s=7~TeV

Using 34.7 pb −1 of data collected with the LHCb detector, the inclusive production of the X (3872) meson in pp collisions at √s=7~TeV is observed for the first time. Candidates are selected in the X (3872)→ J / ψπ + π − decay mode, and used to measure "Equation missing" where σ ( pp → X (3872)+anything) is the inclusive production cross section of X (3872) mesons with rapidity in the range 2.5–4.5 and transverse momentum in the range 5–20 GeV/ c . In addition the masses of both the X (3872) and ψ (2 S ) mesons, reconstructed in the J / ψπ + π − final state, are measured to be mX(3872) = 3871.95 ±0.48 \ (stat) ±0.12 \ (syst)\ MeV/c² and mψ(2S) = 3686.12±0.06 \ (stat) ±0.10 \ (syst)\ MeV/c².