photon+jet process application for setting the absolute jet energy and determining the gluon distribution at the Tevatron Run II

TL;DR

This paper investigates improved methods for calibrating jet energy and determining the gluon distribution at the Tevatron using photon+jet events, demonstrating that optimized cuts can enhance accuracy and extend the kinematic reach.

Contribution

It introduces new selection criteria for photon+jet events that improve jet energy calibration and enables probing the gluon distribution at lower x and higher Q^2 than previous experiments.

Findings

Optimized cuts increase background suppression efficiency.

Photon+Jet samples are sufficient for gluon distribution analysis.

Extended kinematic range beyond HERA's measurements.

Abstract

We study the effect of application of new set of cuts, proposed in our previous works, on the improvement of accuracy of the jet energy calibration with p p->photon+Jet+X process at Tevatron. Monte Carlo events produced by the PYTHIA 5.7 generator are used for this aim. The selection criteria for photon+Jet event samples that would provide a good balance of photon and jet transverse momenta and would allow to reduce the background are described. The distributions of these events over photon transverse momenta and jet pseudorapidity are presented. The features of photon+Jet events in the central calorimeter region of the D0 detector (eta_jet < 0.7) are exposed. The efficiency of the cuts used for background suppression is demonstrated. It is shown that the samples of photon+Jet events, gained with the cuts for the jet energy calibration, may have enough statistics for determining the gluon distribution inside a proton in the region of x < 10^{-3} and of Q^2 by one order higher than that studied at HERA.