Medium modification of the charge-weighted Energy-Energy Correlators in Pb+Pb collisions at $\sqrt{s_{NN}}=5.02$~TeV

TL;DR

This paper investigates how the medium created in Pb+Pb collisions at 5.02 TeV modifies charge-dependent jet substructure, revealing universal patterns and enhanced opposite-charge correlations at small angles due to jet quenching.

Contribution

It introduces a systematic analysis of charge-weighted Energy-Energy Correlators in heavy-ion collisions, uncovering flavor-independent medium modifications and the origin of V-shaped charge correlation patterns.

Findings

Medium modifications are significant and flavor-independent.

Jet quenching enhances small-angle opposite-charge correlations.

A V-shaped pattern in charge correlations is identified as energy-weighting effects.

Abstract

We present a systematic study of medium-induced modifications in charge-dependent jet substructure using the charge-weighted Energy-Energy Correlators (EEC) in p+p and 0-10\% central Pb+Pb collisions at a center-of-mass energy of 5.02 TeV. Charged hadron jets as well as flavor separated quark and gluon-initiated jets with momentum 40-60 GeV and R=0.4 are analyzed. The ratio of the charge-weighted distribution to the inclusive EEC, which reflects the magnitude of charge correlations, is consistently negative, demonstrating the dominance of opposite-charge pairs due to charge conservation. In Pb+Pb collisions, significant medium modifications are observed. The A+A to p+p ratio for charge correlations exhibits a universal pattern across jet types, showing no flavor dependence. Jet quenching enhances opposite-charge correlations at small angles while reducing them at large angles, leading to a steeper angular distance RL dependence of charge correlations in A+A, indicating a more rapid decorrelation behavior as RL increases. A distinctive V-shaped modification pattern appears in the plateau-like enhancement in the transition and small-RL region, independent of jet flavor. Through factorization of the EEC into charged hadron pair multiplicity and average energy weighting distributions, we identify enhanced energy weighting of opposite-charge pairs at small RL as the origin of the V-shaped modification. Also, the plateau-like enhancement of charge correlations is found to be unrelated to selection bias effects.