Direct-photon plus away-side jet production inpp collisions at\(\sqrt s = 63\) GeV and a determination of the gluon distribution

We have determined the double inclusive cross-section for opposite-side high-p T photons and away-side jets withθ γ ≈θjet≈90° produced inpp collisions at the CERN Intersecting Storage Rings at\(\sqrt s = 63\) GeV. Under the assumption that these events arise predominantly from the QCD gluon Compton process we have calculated the gluon structure function in the range 0.15≦x≦0.30 at an average square of the four-momentum transfer of 40 GeV2/c2. The data favour a soft gluon distribution in the proton.