J/ψ and ψ(2s) Production pp collisions at √ s = 1.8TeV

Abstract

We present a study of $J/\ensuremath{\psi}$ and $\ensuremath{\psi}(2S)$ production in $p\overline{p}$ collisions, at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ with the CDF detector at Fermilab. The $J/\ensuremath{\psi}$ and $\ensuremath{\psi}(2S)$ mesons are reconstructed using their ${\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decay modes. We have measured the inclusive production cross section for both mesons as a function of their transverse momentum in the central region, $|\ensuremath{\eta}|l0.6$. We also measure the fraction of these events originating from $b$ hadrons. We thus extract individual cross sections for $J/\ensuremath{\psi}$ and $\ensuremath{\psi}(2S)$ mesons from $b$-quark decays and prompt production. We find a large excess (approximately a factor of 50) of direct $\ensuremath{\psi}(2S)$ production compared with predictions from the color singlet model.