In-medium modification of dijets in PbPb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV

TL;DR

This study investigates how high-energy jets are modified when passing through quark-gluon plasma in lead-lead collisions, revealing that jet modifications depend on the momentum balance between dijets and differ for leading and subleading jets.

Contribution

It provides new insights into in-medium jet modifications in heavy-ion collisions, especially how these modifications vary with dijet momentum imbalance and differ between leading and subleading jets.

Findings

Significant modifications in charged-particle distributions for balanced dijets.

Reduced modifications for leading jets in imbalanced dijet events.

Modifications depend on the dijet momentum ratio $x_j$.

Abstract

Modifications to the distribution of charged particles with respect to high transverse momentum ($p_\mathrm{T}$) jets passing through a quark-gluon plasma are explored using the CMS detector. Back-to-back dijets are analyzed in lead-lead and proton-proton collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV via correlations of charged particles in bins of relative pseudorapidity and angular distance from the leading and subleading jet axes. In comparing the lead-lead and proton-proton collision results, modifications to the charged-particle relative distance distribution and to the momentum distributions around the jet axis are found to depend on the dijet momentum balance $x_j$, which is the ratio between the subleading and leading jet $p_\mathrm{T}$. For events with $x_j$ $\approx$ 1, these modifications are observed for both the leading and subleading jets. However, while subleading jets show significant modifications for events with a larger dijet momentum imbalance, much smaller modifications are found for the leading jets in these events.