Imaging the Wakes of Jets with Energy-Energy-Energy Correlators

Abstract

As the partons in a jet propagate through the quark-gluon plasma (QGP) produced in a heavy-ion collision, they lose energy to, kick, and are kicked by the medium. The resulting modifications to the parton shower encode information about the microscopic nature of QGP. The momentum and energy lost by the parton shower are gained by the medium and, since QGP is a strongly coupled liquid, this means that the jet excites a wake in the droplet of QGP. After freezeout, this wake becomes soft hadrons with net momentum in the jet direction meaning that reconstructed jets include hadrons originating from both the modified parton shower and its wake. This makes it challenging to find an unambiguous experimental view of the response of a droplet of QGP to a jet. Recent years have seen significant advances in the understanding of the substructure of jets using correlation functions of the energy flux operator. So far, such studies have focused primarily on the two-point correlator, which serves to identify the angular scale of the underlying dynamics. Higher-point correlators hold the promise of mapping out the dynamics themselves. We perform the first study of the shape-dependent three-point energy-energy-energy correlator in heavy-ion collisions. Using the Hybrid Model to simulate the interactions of high energy jets with QGP, we show that hadrons originating from wakes are the dominant contribution to the three-point correlator in the regime where the three points are well-separated in angle, forming a roughly equilateral triangle. This equilateral region of the correlator is far from the region populated by collinear vacuum emissions, making it a canvas on which jet wakes can be imaged. Our work is a key step towards the systematic use of energy correlators to image and unravel the dynamical response of a droplet of QGP to a passing jet, and motivates many experimental and theoretical studies.