On the application of 'photon+jet' process for setting the absolute scale of jet energy and determining the gluon distribution at the Tevatron in Run II

The consequences of application of new set of criteria, proposed in our previous works, for the improvement of a jet energy calibration accuracy with the process "p~p->photon+jet+X" at Tevatron and for a reduction of background events contribution are studied. The efficiencies of the used selection criteria are estimated. The distributions of these events over photon Pt and jet pseudorapidity are presented. The features of "photon+jet" events in the central calorimeter region of the D0 detector (|\eta|<0.7) are investigated. It is also shown that the samples of "photon+jet" events, selected with the cuts used for the jet energy calibration, may have the statistics sufficient for determining the gluon distribution function of a proton in the region of 2*10^{-3}< x < 1.0 and the values of Q^2 by one order higher than that reached in the experiments at HERA. Monte Carlo events produced by the PYTHIA 5.7 generator are used for this aim.