Diffusion Wake: A Distinctive Consequence of the Mach-Cone Wake Induced by Supersonic Jets in High-Energy Heavy-Ion Collisions

In this Research Perspective, we briefly review the diffusion wake, a distinctive consequence of the Mach-cone wake induced by the supersonic jets in ultrarelativistic heavy-ion collisions. The diffusion wake depletes soft hadrons in the direction opposite to the propagating jet. According to coupled transport and hydrodynamic simulations, a valley in the 2-dimensional jet–hadron correlation in azimuthal angle and rapidity arises on the top of the multiple-parton interaction ridge as an unambiguous signal of the diffusion wake induced by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>γ</mml:mi> </mml:math> -jets in heavy-ion collisions. In dijet events with a finite rapidity gap, the rapidity asymmetry of the jet–hadron correlation has been shown to be a robust signal of the diffusion wake. The same rapidity asymmetry can also be applied to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mi>γ</mml:mi> </mml:math> -jet events, and both are background-free. Experimental measurements of these signals can provide valuable insights into the properties of the quark–gluon plasma formed in high-energy heavy-ion collisions.