Observation of Exclusive Charmonium Production and γγ→μ+μ- in pp̅ Collisions at √s=1.96 TeV

In CDF we have observed the reactions p + p → p + X + p, with X being a centrally produced J/ψ, ψ(2S), or χ c0 , and γγ → μ + μ ― in pp collisions at √s = 1.96 TeV. The event signature requires two oppositely charged central muons, and either no other particles or one additional photon detected. Exclusive vector meson production is as expected for elastic photoproduction, γ + p → J/ψ(ψ(2S)) + p, observed here for the first time in hadron-hadron collisions. We also observe exclusive χ c0 → J/ψ + y. The cross sections dσ/dy I y=0 for J/ψ, ψ(2S), and χ c0 are 3.92 ± 0.25(stat) ± 0.52(syst) nb, 0.53 ± 0.09(stat) ± 0.10(syst) nb, and 76 ± 10(stat) ± 10(syst) nb, respectively, and the continuum is consistent with QED. We put an upper limit on the cross section for Odderon exchange in exclusive J/ψ production.