Measurements of the charm jet cross section and nuclear modification factor in pPb collisions at sqrt(s[NN]) = 5.02 TeV

TL;DR

This paper reports the first measurement of charm jet production cross sections and nuclear modification factors in pPb collisions at 5.02 TeV, showing no significant energy loss effects and consistent charm jet fractions with theoretical predictions.

Contribution

It provides the first differential cross section measurements of charm jets in pPb collisions and compares them with pp results to evaluate nuclear effects.

Findings

Nuclear modification factor R[pA] is approximately 0.92, indicating no strong suppression.

Charm jet fraction matches PYTHIA 6 predictions and remains constant across jet transverse momentum.

Results suggest the absence of significant final-state energy loss for charm quarks in pPb collisions.

Abstract

The CMS Collaboration presents the first measurement of the differential cross section of jets from charm quarks produced in proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of sqrt(s[NN]) = 5.02 TeV, as well as results from charm quark jets in proton-proton (pp) collisions at sqrt(s) = 2.76 and 5.02 TeV. By comparing the yields of the pPb and pp collision systems at the same energy, a nuclear modification factor for charm jets from 55 to 400 GeV/c in pPb collisions at sqrt(s[NN]) = 5.02 TeV of R[pA] = 0.92 +/- 0.07 (stat) +/- 0.11 (syst) is obtained. This is consistent with an absence of final-state energy loss for charm quarks in pPb collisions. In addition, the fraction of jets coming from charm quarks is found to be consistent with that predicted by PYTHIA 6 for pp collisions at sqrt(s)= 2.76 and 5.02 TeV, and is independent of the jet transverse momentum from 55 to 400 GeV/c.