Visualizing How Jet Structure Shapes Jet Wakes

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.