We present a study of $J/\psi$ and $\psi \left(2S\right)$ production in $p\overline{p}$ collisions, at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$ with the CDF detector at Fermilab. The $J/\psi$ and $\psi \left(2S\right)$ mesons are reconstructed using their ${\mu }^{+}{\mu }^{-}$ decay modes. We have measured the inclusive production cross section for both mesons as a function of their transverse momentum in the central region, $|\eta |<0.6\mathrm{}$. We also measure the fraction of these events originating from $b$ hadrons. We thus extract individual cross sections for $J/\psi$ and $\psi \left(2S\right)$ mesons from $b$-quark decays and prompt production. We find a large excess (approximately a factor of 50) of direct $\psi \left(2S\right)$ production compared with predictions from the color singlet model.

• Received 3 February 1997

DOI:https://doi.org/10.1103/PhysRevLett.79.572