photon+jet event rate estimation for the gluon distribution determination at the Tevatron Run II

Abstract

Since a lot of theoretical predictions on the production of new particles (Higgs, SUSY) at the Tevatron are based on model estimations of the proton gluon density behavior at low $x$ and high values of a transfered momentum Q^2, the study of a possibility of a measurement of the gluon density in this kinematic region directly in Tevatron experiments is obviously of a big interest [1]. Basing on the selection criteria proposed ealier in [1,2], the background events suppression factors and corresponding signal events selection efficiencies are determined here. The estimation of the number of photon+jet events suitable for measurement of gluon distribution in different x and Q^2 intervals at Tevatron Run II is also done. It is shown that with integrated luminosity L_{int}=3 fb^-1 it would be possible to collect about one million of these events. This number would allow to cover a new kinematical region, 10^-3 < x < 1.0 with 1.6*10^3 < Q^2 < 2*10^4 (GeV/c)^2, not studied in any previous experiment. This area includes the values of Q^2 that are, on the average, by about one order of magnitude higher than those reached at HERA now. The rates of g c-> photon + jet events are also obtained.