Production of J/ψ and ψ(2S) mesons in π-Be collisions at 515 GeV/c

We have studied the production of J/ψ and ψ(2S) charmonium mesons in 515 GeV/c π-Be collisions in the Feynman-x range 0.1<x_f<0.8. J/ψ mesons were detected via their decay into µ⁺µ-, and ψ(2S) mesons were studied in both the µ⁺µ- and J/ψ π+π- decay modes. J/ψ differential cross sections have been measured as functions of (formula presented)≳0.1. Our results are compared with those from other experiments performed at lower beam energies. We also measure the differential ψ(2S) cross section as a function of both (formula presented), and a ψ(2S) inclusive cross section of B(ψ(2S)→J/ψ(formula presented)Be→ψ(2S)+X)/A=[7. 4±1.5(stat)±1.2(syst)] nb/nucleon for ψ(2S) (formula presented)≳0.1. The fraction of the inclusive J/ψ yield due to ψ(2S) meson decays is 0.083±0.017(stat) ±0.013(syst), and the observed ratio of ψ(2S) decay rates is B(ψ(2S)→J/ψ(formula presented)) =30.2±7.2(stat)±6.8(syst). We have searched for production of “hidden” charm resonances decaying into either J/ψ(formula presented),ψ(2S)(formula presented), or J/ψ(formula presented) systems, and report an upper limit of 3.1 nb/nucleon for the product of branching ratio and cross section for the recently reported enhancement at a J/ψ(formula presented).