Abstract

Modifications of the properties of jets in PbPb collisions, relative to those in pp collisions, are studied at a nucleon-nucleon center-of-mass energy of sqrt{s_{mathrm{N};mathrm{N}}}=5.02 TeV via correlations of charged particles with the jet axis in relative pseudorapidity (Δη), relative azimuth (Δϕ), and relative angular distance from the jet axis varDelta mathrm{r}=sqrt{{left(varDelta eta right)}^2+{left(varDelta phi right)}^2} . This analysis uses data collected with the CMS detector at the LHC, corresponding to integrated luminosities of 404 μb−1 and 27.4 pb−1 for PbPb and pp collisions, respectively. Charged particle number densities, jet fragmentation functions, and jet shapes are presented as a function of PbPb collision centrality and charged-particle track transverse momentum, providing a differential description of jet modifications due to interactions with the quark-gluon plasma.

Highlights

  • Background subtractionTotal dominate the mixed event corrected signal and, the signal is expected to be uniform for |∆η| > 1.5

  • For PbPb events with centrality 0–10%, the correlated yield is increased relative to pp collisions at low pT by up to a factor of two. In addition to these charged-particle yields, we examine the jet transverse momentum profile P(∆r) and the jet shape ρ(∆r) variables, defined using the distribution of chargedparticle tracks in annular rings around the jet axis, with each particle weighted by its ptTrk value

  • A redistribution of energy from small to large angles from the jet axis is observed for PbPb relative to pp events, with the most pronounced effect seen for central collisions

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Summary

Introduction

Background subtractionTotal dominate the mixed event corrected signal and, the signal is expected to be uniform for |∆η| > 1.5. CMS Jet shapes pp 27.4 pb-1 (5.02 TeV) PbPb 404 μb-1 (5.02 TeV)

Results
Conclusion
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