  We have observed the reactions p+pbar --> p+X+pbar, with X being a centrally
produced J/psi, psi(2S) or chi_c0, and gamma+gamma --> mu+mu-, in proton-
antiproton collisions at sqrt{s} = 1.96 TeV using the Run II Collider Detector
at Fermilab. The event signature requires two oppositely charged muons, each
with pseudorapidity |eta| < 0.6, with M(mumu) in [3.0,4.0] GeV/c2, and either
no other particles, or one additional photon, detected. The J/psi and the
psi(2S) are prominent, on a continuum consistent with the QED process
gamma+gamma --> mu+mu-. Events with a J/psi and an associated photon candidate
are consistent with exclusive chi_c0 production through double pomeron
exchange. The exclusive vector meson production is as expected for elastic
photo- production, gamma+p --> J/psi(psi(2S)) + p, which is observed here for
the first time in hadron-hadron collisions. The cross sections ds/dy(y=0) for p
+ pbar --> p + X + pbar with X = J/psi, psi(2S) orchi_c0 are 3.92+/-0.62 nb,
0.53+/-0.14 nb, and 75+/-14 nb respectively. The cross section for the
continuum, with |eta(mu+/-)| < 0.6 and M(mumu) in [3.0,4.0] GeV/c2, is
2.7+/-0.5 pb, consistent with QED predictions. We put an upper limit on the
cross section for odderon exchange in J/psi production: ds/dy(y=0) (J/psi_O/IP)
< 2.3 nb at 95% C.L.

High Energy Physics - Experiment