# Study of jet quenching with Z+jet correlations in PbPb and pp collisions at sqrt(s[NN]) = 5.02 TeV

## TL;DR

This paper investigates how jets associated with Z bosons are affected in lead-lead versus proton-proton collisions at 5.02 TeV, revealing energy loss effects in the quark-gluon plasma.

## Contribution

First measurement of Z+jet correlations in PbPb collisions at the LHC, comparing to pp collisions to study jet quenching effects.

## Key findings

- R[jz] is smaller in PbPb than in pp collisions.
- Partons lose energy in the quark-gluon plasma, reducing jet yields.
- Jet energy imbalance increases in PbPb collisions.

## Abstract

The production of jets in association with Z bosons, reconstructed via the mu+mu- and e+e- decay channels, is studied in pp and, for the first time, in PbPb collisions. Both data samples were collected by the CMS experiment at the LHC, at a nucleon-nucleon center-of-mass energy of 5.02 TeV. The PbPb collisions were analyzed in the 0-30% centrality range. The back-to-back azimuthal alignment was studied in both pp and PbPb collisions for Z bosons with transverse momentum p[tz] > 60 GeV/c and a recoiling jet with p[tj] > 30 GeV/c. The pt imbalance, x[jz] = p[tj] / p[tz], as well as the average number of jet partners per Z, R[jz], were studied in intervals of p[tz], in both pp and PbPb collisions. The R[jz] is found to be smaller in PbPb than in pp collisions, which suggests that in PbPb collisions a larger fraction of partons, associated with the Z bosons, lose energy and fall below the 30 GeV/c p[tj] threshold.