Leading jet cross sections at small transverse momenta in pp collisions at √s = 8 TeV

Abstract

The production yield of leading charged-particle jets in proton-proton collisions is measured at √s = 8 TeV based on a data sample collected with the CMS detector and corresponding to an integrated luminosity of 45μb^-1. The charged-particle jets are measured in the pseudorapidity range |η| < 1.9 for transverse momenta p_T > 1 GeV. The measured yields integrated above a given minimum transverse momentum p_T,min provide information on the mechanism by which the underlying parton-parton cross sections are unitarised approaching the low-p_T non-perturbative domain. Predictions obtained from various Monte Carlo event generators are compared to the measurements. A large model sensitivity is seen.

Figures

Figure caption: Normalised integrated event cross-sections as a function of p_T,min, for events with a leading charged-particle jet with p_T,jet > p_T,min. Leading jets are selected as the highest-p_T jet from the collection of charged-particle jets with p_T > 1 GeV and |η| < 1.9. The data are compared to predictions from various Pythia 6 tunes (left) and various Monte Carlo event generators (right). The error bars indicate the statistical uncertainty and the shaded area the systematic uncertainty. The systematic uncertainties are only shown in the ratio plot. The data are normalized to number of events with a leading central track with p_T>0.4 GeV (σ_vis). The Monte Carlo predictions are scaled to the measured value of σ(p_{T,leading~ch. jet} > 14.3 GeV) / σ_vis . The uncertainties shown in the ratio plots are thus rescaled with respect to the normalisation of the Monte Carlo predictions.

Related - Measurement of leading charged particle cross-sections

Figure caption: Normalised integrated event cross-sections as a function of p_T,min, for events with a leading charged particlewith p_T > p_T,min. Leading charged particles are selected as the highest-p_T charged particle from the collection of charged particles with p_T > 0.8 GeV and |η| < 2.4. The data are compared to predictions from various Pythia 6 tunes (left) and various Monte Carlo event generators (right). The Monte Carlo curves are scaled to the measured value of σ(p_{T,leading~ch. particle} > 9 GeV) / σ_vis . The data points are taken from CMS-PAS-FSQ-12-026 (included here for completeness and with the same comparison to predictions as for the leading charged particle-jets).