Observation of Exclusive Charmonium Production and gamma gamma -> mu+ mu- in p anti-p Collisions at s**(1/2) =1.96 TeV

We have observed the reactions p + p-bar --> p + X + p-bar, with X being a centrally produced J/psi, psi(2S) or chi(c)0, and gamma gamma --> mu+ mu-, in proton-antiproton collisions at s**(1/2) =1.96 TeV using the Run II Collider Detector at Fermilab. The event signature requires two oppositely charged muons, each with pseudorapi+dity |eta| < 0.6, with M_mu mu epsilon [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(c)0 production through double pomeron exchange. The exclusive vector meson production is as expected for elastic photoproduction, gamma + p -> J/psi(psi(2S)) + p, which is observed here for the first time in hadron-hadron collisions. The cross section d sigma/dy|_y y= for p + p-bar -> p + X + p-bar with x J/psi, psi(2S) or chi(c)0 are 3.92 +/- 0.62 nb, 0.53 +/- 0.14 nb, and 76 +/- 14 nb, respectively. The cross section for the continuum, with |eta(mu+/-)| < 0.6 M_mu mu epsilon [3.0, 4.0] GeV/c2, is int d sigma/dM.d_eta1.d_eta2 2.7 +/- 0.5 pb, consistent with QED prediction. We put an upper limit on the cross section for oderon exchange in exclusive J/psi production: d sigma/dy|_y y=0(J/psi_OP) < 2.3 nb at 95% C.