Measurement of the ratio of inclusive jet cross sections using the anti-kt algorithm with radius parameters R = 0.5 and 0.7 in pp collisions at sqrt(s) = 7 TeV

TL;DR

This paper measures the ratio of inclusive jet cross sections for two different jet radius parameters in proton-proton collisions at 7 TeV, revealing discrepancies with some theoretical models but agreement with NLO matched simulations.

Contribution

It provides the first detailed measurement of the ratio of inclusive jet cross sections for R=0.5 and 0.7 at 7 TeV, testing QCD predictions and Monte Carlo models.

Findings

Significant discrepancies with leading-order and fixed-order NLO calculations.

Next-to-leading-order matrix element simulations matched to parton showers agree well with data.

The ratio varies with jet rapidity and transverse momentum.

Abstract

Measurements of the inclusive jet cross section with the anti-kt clustering algorithm are presented for two radius parameters, R=0.5 and 0.7. They are based on data from LHC proton-proton collisions at sqrt(s) = 7 TeV corresponding to an integrated luminosity of 5.0 inverse femtobarns collected with the CMS detector in 2011. The ratio of these two measurements is obtained as a function of the rapidity and transverse momentum of the jets. Significant discrepancies are found comparing the data to leading-order simulations and to fixed-order calculations at next-to-leading order, corrected for nonperturbative effects, whereas simulations with next-to-leading-order matrix elements matched to parton showers describe the data best.