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.
Highlights
The inclusive cross section for jets produced with high transverse momenta in proton-proton collisions is described by quantum chromodynamics (QCD) in terms of parton-parton scattering
The analysis presented here focuses on the study of the jet radius ratio, Rð0.5; 0.7Þ, as a function of the jet pT and rapidity y, using the anti-kT jet algorithm with R 1⁄4 0.5 as the alternative and R 1⁄4 0.7 as the reference jet radius
Each source of systematic uncertainty is assumed to be fully correlated between the R 1⁄4 0.5 and 0.7 cross section measurements, which is supported by closure tests
Summary
The inclusive cross section for jets produced with high transverse momenta in proton-proton collisions is described by quantum chromodynamics (QCD) in terms of parton-parton scattering. The inclusive jet measurements with jet size parameters R on the order of unity performed by the CDF [10,11,12] and D0 [13,14,15] Collaborations at 1.8 and 1.96 TeV center-of-mass energies are well described by NLO QCD calculations. Even though calculations at NLO provide at most three partons in the final state for jet clustering, measurements with somewhat smaller anti-kT jet radii of R 1⁄4 0.4 up to 0.7. The relative normalization of measured cross sections and theoretical predictions for different jet radii R exhibits a dependence on R. This effect has been investigated theoretically in Refs. Comparisons to predictions involving POWHEG have been presented previously by ATLAS [16]
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