Measurement of the double-differential inclusive jet cross section in proton-proton collisions at sqrt(s) = 13 TeV

TL;DR

This CMS study measures the double-differential inclusive jet cross section in 13 TeV pp collisions, using two jet sizes (R=0.7 and 0.4) and unfolding to particle level. It compares results to NLO pQCD predictions with nonperturbative and electroweak corrections, and to MC models with parton showers and MPI; Powheg+Pythia8 matches both jet radii, while fixed-order NLO describes R=0.7 well but overestimates R=0.4 by 5–10%. The analysis confirms that jet physics at 13 TeV is as well understood as at lower energies within the explored phase space. NP corrections are sizable for larger jets and diminish for smaller ones, illustrating the impact of showering and hadronization on jet observables. Overall, the results support the validity of pQCD and PS-based approaches in describing high-energy jet production and provide crucial benchmarks for PDF and αS studies.

Abstract

A measurement of the double-differential inclusive jet cross section as a function of jet transverse momentum pT and absolute jet rapidity |y| is presented. The analysis is based on proton-proton collisions collected by the CMS experiment at the LHC at a centre-of-mass energy of 13 TeV. The data samples correspond to integrated luminosities of 71 and 44 inverse picobarns for |y| < 3 and 3.2 < |y| < 4.7, respectively. Jets are reconstructed with the anti-kt clustering algorithm for two jet sizes, R, of 0.7 and 0.4, in a phase space region covering jet pT up to 2 TeV and jet rapidity up to |y| = 4.7. Predictions of perturbative quantum chromodynamics at next-to-leading order precision, complemented with electroweak and nonperturbative corrections, are used to compute the absolute scale and the shape of the inclusive jet cross section. The cross section difference in R, when going to a smaller jet size of 0.4, is best described by Monte Carlo event generators with next-to-leading order predictions matched to parton showering, hadronisation, and multiparton interactions. In the phase space accessible with the new data, this measurement provides a first indication that jet physics is as well understood at sqrt(s) = 13 TeV as at smaller centre-of-mass energies.

Figures (9)

• Figure 1: Fits to the nonperturbative corrections obtained for inclusive AK7 jet cross sections as a function of jet $p_{\mathrm{T}}\xspace$ for two rapidity bins: $0.5 < \lvert y \rvert < 1.0$ (left) and $2.5 < \lvert y \rvert < 3.0$ (right). The dotted lines represent the uncertainty bands, which are evaluated by fitting the envelopes of the predictions of the different generators used.
• Figure 2: Fits to the nonperturbative corrections obtained for inclusive AK4 jet cross sections as a function of jet $p_{\mathrm{T}}\xspace$ for two rapidity bins: $0.5 < \lvert y \rvert < 1.0$ (left) and $2.5 < \lvert y \rvert < 3.0$ (right). The dotted lines represent the uncertainty bands, which are evaluated by fitting the envelopes of the predictions of the different generators used.
• Figure 3: Electroweak correction factors for the seven rapidity bins for the AK7 (left) and AK4 (right) jets as a function of jet $p_{\mathrm{T}}\xspace$.
• Figure 4: Double-differential inclusive jet cross section as function of jet $p_{\mathrm{T}}$. On the left, data (points) and predictions from NLOJet++ based on the CT14 PDF set corrected for the NP and electroweak effects (line) are shown. On the right, data (points) and predictions from powheg (PH) + pythia8 (P8) with tune CUETM1 (line) are shown. Jets are clustered with the anti-$k_{\mathrm{t}}$ algorithm ($R = 0.7$).
• Figure 5: Double-differential inclusive jet cross section as function of jet $p_{\mathrm{T}}$. On the left, data (points) and predictions from NLOJet++ based on the CT14 PDF set corrected for the NP and electroweak effects (line) are shown. On the right, data (points) and predictions from powheg (PH) + pythia8 (P8) with tune CUETM1 (line) are shown. Jets are clustered with the anti-$k_{\mathrm{t}}$ algorithm ($R = 0.4$).