Psi production in p-barN and pi -N interactions at 125 GeV/c and a determination of the gluon structure functions of the p-bar and the pi -

Abstract

We have measured the cross section for production of [psi] and [psi][prime] in [ital [bar p]] and [pi][sup [minus]] interactions with Be, Cu, and W targets in experiment E537 at Fermilab. The measurements were performed at 125 GeV/[ital c] using a forward dimuon spectrometer in a closed geometry configuration. The gluon structure functions of the [ital [bar p]] and [pi][sup [minus]] have been extracted from the measured [ital d][sigma]/[ital dx][sub [ital F]] spectra of the produced [psi]'s. From the [ital [bar p]]W data we obtain, for [ital [bar p]], [ital xG]([ital x])=(2.15[plus minus]0.7)[1[minus][ital x]][sup (6.83[plus minus]0.5)] [1+(5.85[plus minus]0.95)[ital x]]. In the [pi][sup [minus]] case, we obtain, from the W and the Be data separately, [ital xG]([ital x])=(1.49[plus minus]0.03)[1[minus][ital x]][sup (1.98[plus minus]0.06)] (for [pi][sup [minus]]W), [ital xG]([ital x])=(1.10[plus minus]0.10)[1[minus][ital x]][sup (1.20[plus minus]0.20)] (for [pi][sup [minus]]Be).