Measurement of<i>J</i>/ψ and ψ’ production in 800 GeV/<i>c</i>proton-gold collisions

Abstract

With a data sample containing 1.1\ifmmode\times\else\texttimes\fi{}${10}^{5}$ J/\ensuremath{\psi}\ensuremath{\rightarrow}${\mathrm{\ensuremath{\mu}}}^{+}$${\mathrm{\ensuremath{\mu}}}^{\mathrm{\ensuremath{-}}}$ decays reconstructed with 16 MeV/${\mathit{c}}^{2}$ rms mass resolution, we have measured the differential cross sections versus Feynman-x, rapidity, and ${\mathit{p}}_{\mathit{T}}$ for the production of J/\ensuremath{\psi} and \ensuremath{\psi}' in 800 GeV/c p-Au collisions. Our results are compared with leading-order QCD predictions and with previous measurements. While the shapes of the cross sections are in qualitative agreement with QCD predictions, the magnitudes disagree by factors of 7 (J/\ensuremath{\psi}) and 25 (\ensuremath{\psi}'). Assuming an appropriate form for the differential cross sections in regions not measured we derive a total J/\ensuremath{\psi} production cross section \ensuremath{\sigma}(p+N\ensuremath{\rightarrow}J/\ensuremath{\psi}+X)=442\ifmmode\pm\else\textpm\fi{}2\ifmmode\pm\else\textpm\fi{}88 nb/nucleon and a (model-dependent) total \ensuremath{\psi}' cross secton \ensuremath{\sigma}(p+N\ensuremath{\rightarrow}\ensuremath{\psi}'+X)=75\ifmmode\pm\else\textpm\fi{}5\ifmmode\pm\else\textpm\fi{}22 nb/nucleon. For J/\ensuremath{\psi} produced at central rapidity, d\ensuremath{\sigma}(p+N\ensuremath{\rightarrow}J/\ensuremath{\psi}+X)/dy${\mathrm{\ensuremath{\Vert}}}_{\mathit{y}=0}$=230\ifmmode\pm\else\textpm\fi{}5\ifmmode\pm\else\textpm\fi{}46 nb/nucleon.