Head shock vs Mach cone: azimuthal correlations from 2 to 3 parton processes in relativistic heavy-ion collisions

TL;DR

This paper investigates how energy-momentum from fast partons affects azimuthal correlations in heavy-ion collisions, proposing that 2 to 3 parton processes can explain the double-hump structure without relying on Mach cones.

Contribution

It introduces a model where double-hump azimuthal correlations arise from two away-side partons depositing energy-momentum, challenging the Mach cone explanation.

Findings

Double-hump structure can be produced by two partons, not Mach cones.

Model reproduces the decreasing away-side correlation with increasing associated hadron momentum.

Energy is mainly deposited along the head shock of fast partons.

Abstract

We study the energy-momentum deposited by fast moving partons within a medium using linearized viscous hydrodynamics. The particle distribution produced by this energy-momentum is computed using the Cooper-Frye formalism. We show that for the conditions arising in heavy-ion collisions, energy momentum is preferentially deposited along the head shock of the fast moving partons. We also show that the double hump in the away-side of azimuthal correlations can be produced by two (instead of one) away-side partons that deposit their energy-momentum along their directions of motion. These partons are originated in the in-medium hard scattering in 2 to 3 processes. We compare the results of the analysis to azimuthal angular correlations from PHENIX and show that the calculation reproduces the data systematics of a decreasing away-side correlation when the momentum of the associated hadron becomes closer to the momentum of the leading hadron. This scenario seems to avoid the shortcomings of the Mach cone as the origin of the double-hump structure in the away-side