Jets, Mach cone, hot spots, ridges, harmonic flow, dihadron and $\gamma$-hadron correlation in high-energy heavy-ion collisions

TL;DR

This study uses the AMPT model to analyze how hot spots and harmonic flows influence dihadron correlations, revealing a double-peak structure linked to jet-induced Mach cones and hot spots, independent of initial geometry.

Contribution

It demonstrates that hot spots and harmonic flows significantly affect dihadron correlations, and isolates jet-induced Mach cone effects from flow contributions using azimuthal randomization.

Findings

Double-peak dihadron correlation persists after flow subtraction.

Hot spots cause a near-side ridge with large rapidity gap.

Mach cone effects are isolated in gamma-hadron correlations.

Abstract

Within the AMPT Monte Carlo model, hot spots in the initial transverse parton density are shown to lead to harmonic flows which all contribute to dihadron azimuthal correlation. The net back-to-back dihadron correlation after subtraction of harmonic flows still has a double-peak that is independent of the initial geometric triangularity at a fixed impact-parameter and unique to the structure of jet-induced Mach cone and expanding hot spots dragged by radial flow. The longitudinal structure of hot spots also leads to a near-side ridge in dihadron correlation with a large rapidity gap. By successively randomizing the azimuthal angle of the transverse momenta and positions of initial partons, one can isolate the effects of jet-induced medium excitation and expanding hot spots on the dihadron azimuthal correlation with both small and large rapidity gap. The double-peak in the net dihadron correlation is quantitatively different from that in $\gamma$-hadron that is free of the contributions from harmonic flow and hot spots and caused only by jet-induced Mach cone.