Measurement of the differential cross section for the production of an isolated photon with associated jet in ppbar collisions at sqrt(s)=1.96 TeV

TL;DR

This paper measures the differential cross section for isolated photon production with an associated jet in proton-antiproton collisions at 1.96 TeV, comparing results with QCD predictions and highlighting discrepancies.

Contribution

It provides the first detailed measurement of the differential cross section for photon+jet production at Tevatron energies, testing QCD predictions with high precision.

Findings

Measured differential cross sections across four rapidity regions.

Found discrepancies between data and next-to-leading order QCD predictions.

Compared ratios of cross sections in different regions.

Abstract

The process ppbar -> photon + jet + X is studied using 1.0 fb^-1 of data collected by the D0 detector at the Fermilab Tevatron ppbar collider at a center-of-mass energy sqrt(s)=1.96 TeV. Photons are reconstructed in the central rapidity region |y_gamma|<1.0 with transverse momenta in the range 30<Pt_gamma<400 GeV while jets are reconstructed in either the central |y_jet|<0.8 or forward 1.5<|y_jet|<2.5 rapidity intervals with Pt_jet>15 GeV. The differential cross section d^3sigma/dPt_gamma dy_gamma dy_jet is measured as a function of Pt_gamma in four regions, differing by the relative orientations of the photon and the jet in rapidity. Ratios between the differential cross sections in each region are also presented. Next-to-leading order QCD predictions using different parameterizations of parton distribution functions and theoretical scale choices are compared to the data. The predictions do not simultaneously describe the measured normalization and Pt_gamma dependence of the cross section in any of the four measured regions.