Jet properties in PbPb and pp collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV

TL;DR

This study investigates how jet properties differ between PbPb and pp collisions at 5.02 TeV, revealing modifications caused by interactions with the quark-gluon plasma through detailed correlation measurements.

Contribution

It provides the first differential measurements of jet modifications in PbPb collisions at 5.02 TeV using charged particle correlations with the CMS detector.

Findings

Jet fragmentation functions are softened in PbPb collisions.

Jet shapes show broadening in PbPb relative to pp.

Charged particle densities increase with collision centrality.

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 $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV via correlations of charged particles with the jet axis in relative pseudorapidity ($\Delta \eta$), relative azimuth ($\Delta \phi$), and relative angular distance from the jet axis $\Delta \mathrm{r} = \sqrt{{(\Delta\eta)^{2}+(\Delta\phi)^{2}}}$. This analysis uses data collected with the CMS detector at the LHC, corresponding to integrated luminosities of 404 $\mu$b$^{-1}$ 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.