Observation of Exclusive Charmonium Production and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>γ</mml:mi><mml:mi>γ</mml:mi><mml:mo>→</mml:mo><mml:msup><mml:mi>μ</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:msup><mml:mi>μ</mml:mi><mml:mo>−</mml:mo></mml:msup></mml:math>in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi><mml:mover accent="true"><mml:mi>p</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>Collisions at<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msqrt><mml:mi>s</mml:mi></mml:msqrt><mml:mo>=</mml:mo><mml:mn>1.96</mml:mn><mml:mtext> </mml:mtext><mml:mtext> </mml:mtext><mml:mi>TeV</mml:mi></mml:math>

In CDF we have observed the reactions $p+\overline{p}\ensuremath{\rightarrow}p+X+\overline{p}$, with $X$ being a centrally produced $J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)$, or ${\ensuremath{\chi}}_{c0}$, and $\ensuremath{\gamma}\ensuremath{\gamma}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$. 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, $\ensuremath{\gamma}+p\ensuremath{\rightarrow}J/\ensuremath{\psi}\mathbf{(}\ensuremath{\psi}(2S)\mathbf{)}+p$, observed here for the first time in hadron-hadron collisions. We also observe exclusive ${\ensuremath{\chi}}_{c0}\ensuremath{\rightarrow}J/\ensuremath{\psi}+\ensuremath{\gamma}$. The cross sections $\frac{d\ensuremath{\sigma}}{dy}{|}_{y=0}$ for $J/\ensuremath{\psi}$, $\ensuremath{\psi}(2S)$, and ${\ensuremath{\chi}}_{c0}$ are $3.92\ifmmode\pm\else\textpm\fi{}0.25(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.52(\mathrm{syst})\text{ }\text{ }\mathrm{nb}$, $0.53\ifmmode\pm\else\textpm\fi{}0.09(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.10(\mathrm{syst})\text{ }\text{ }\mathrm{nb}$, and $76\ifmmode\pm\else\textpm\fi{}10(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}10(\mathrm{syst})\text{ }\text{ }\mathrm{nb}$, respectively, and the continuum is consistent with QED. We put an upper limit on the cross section for Odderon exchange in exclusive $J/\ensuremath{\psi}$ production.

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