Measurement of the ratio of three-jet to two-jet cross sections in pp-bar collisions at sqrt(s) = 1.96 TeV

TL;DR

This paper measures the ratio of three-jet to two-jet cross sections in proton-antiproton collisions at 1.96 TeV, comparing results with QCD predictions and event generator models to test theoretical accuracy.

Contribution

It provides the first detailed measurement of the R3/2 ratio at Tevatron energies and evaluates the performance of different QCD models and event generators against the data.

Findings

PYTHIA tunes do not match the data

SHERPA provides a reasonable description

NLO perturbative QCD agrees well with measurements

Abstract

We present a measurement of the ratio of multijet cross sections in pp-bar collisions at sqrt(s) = 1.96 TeV at the Fermilab Tevatron Collider. The measurement is based on a data set corresponding to an integrated luminosity of 0.7 fb-1 collected with the D0 detector. The ratio of the inclusive three-jet to two-jet cross sections, R3/2, has been measured as a function of the jet transverse momenta. The data are compared to QCD predictions in different approximations. Popular tunes of the PYTHIA event generator do not agree with the data, while SHERPA provides a reasonable description of the data. A perturbative QCD prediction in next-to-leading order in the strong coupling constant, corrected for non-perturbative effects, gives a good description of the data.