Double parton interactions in photon+3 jet events in ppbar collisions sqrt{s}=1.96 TeV

TL;DR

This study measures the fraction of double parton scattering events and the effective cross section in photon+3 jet events from proton-antiproton collisions at 1.96 TeV, providing insights into parton densities.

Contribution

First measurement of double parton scattering fraction and effective cross section in photon+3 jet events at Tevatron energies.

Findings

Double parton fraction f_DP ranges from 0.23 to 0.47.

Effective cross section sigma_eff averages 16.4 mb.

Results improve understanding of parton spatial distribution inside nucleons.

Abstract

We have used a sample of photon+3 jets events collected by the D0 experiment with an integrated luminosity of about 1 fb^-1 to determine the fraction of events with double parton scattering (f_DP) in a single ppbar collision at sqrt{s}=1.96 TeV. The DP fraction and effective cross section (sigma_eff), a process-independent scale parameter related to the parton density inside the nucleon, are measured in three intervals of the second (ordered in pT) jet transverse momentum pT_jet2 within the range 15 < pT_jet2 < 30 GeV. In this range, f_DP varies between 0.23 < f_DP < 0.47, while sigma_eff has the average value sigma_eff_ave = 16.4 +- 0.3(stat) +- 2.3(syst) mb.