Is the ridge formed by aligned jet propagation and medium flow?

TL;DR

This paper investigates whether the ridge phenomenon in particle collisions is caused by the interaction between jet propagation and medium flow, analyzing asymmetry in azimuthal correlations from STAR data.

Contribution

It provides the first analysis of azimuthal asymmetry in the ridge, supporting the interplay between jet propagation and medium flow as the ridge formation mechanism.

Findings

Asymmetric ridge observed with maximum at 45°

Jet remains symmetric across all trigger angles

Supports interplay hypothesis for ridge formation

Abstract

Motivated by the recent observation that the ridge decreases with trigger particle angle ($\phi_s$) relative to the event plane, it is theorized that the ridge is formed by interplay between jet propagation and medium flow. Such interplay may produce asymmetry in the ridge azimuthal correlation at a fixed $\phi_s$. We present an analysis of this asymmetry from STAR data. We found an asymmetric ridge with maximum asymmetry at $\phi_s\approx45^{\circ}$ concurrent with a symmetric jet at all $\phi_s$.