Visualizing How Jet Structure Shapes Jet Wakes

¹ Center for Theoretical Physics, Massachusetts Institute of Technology, Cambridge, MA 02139
² DAMTP, University of Cambridge, Cambridge, CB3 0WA, UK
³ IGFAE, Universidade de Santiago de Compostela, E-15782 Galicia - Spain

^* Speaker at HP24; e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
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Published online: 5 November 2025

Abstract

The ATLAS Collaboration has developed a method to analyze largeradius jets composed of skinny R = 0.2 subjets in heavy-ion collisions. We first demonstrate that the measurements pioneered by ATLAS constrain the value of L_res, the resolution length of QGP—and rule out any picture in which an entire parton shower loses energy coherently as a single entity. We then analyze the response of the medium to the passage of large-radius R = 2 jets containing two skinny subjets in gamma-jet events. We introduce novel jet-shape observables that allow us to visualize how the internal structure of large-radius jets shapes the wakes they excite in the QGP. We find that even when the subjets are ∼ 0.8 radians apart, the angular shape of the soft hadrons originating from their wake forms a single broad structure. Only when the two subjets are even farther apart are two sub-wakes revealed. We show that the way in which jet structure shapes the structure of jet-induced wakes can be visualized with similar clarity in experiments by using only low-p_T hadrons. The observables we introduce offer a new and distinctive way of seeing jet-induced wakes – and wake substructure – in heavy-ion collision data.