On the Origin of the "Ridge" phenomenon induced by Jets in Heavy Ion Collisions

TL;DR

The paper explains the 'ridge' phenomenon in heavy ion collisions as a result of jet quenching and hydrodynamical flow, with particles produced by QCD bremsstrahlung being boosted by transverse flow, matching observed correlations.

Contribution

It provides a parameter-independent explanation for the ridge phenomenon linking jet quenching and hydrodynamics in heavy ion collisions.

Findings

Reproduces the angular shape and width of the ridge

Shows particles are produced by QCD bremsstrahlung and boosted by flow

Explains the correlation between jet direction and radial flow

Abstract

We argue that "ridge" in 2-particle correlation function associated with hard trigger at RHIC heavy ion collisions is naturally explained by an interrelation of jet quenching and hydrodynamical transverse flow. The excess particles forming the ridge are produced by QCD bremsstrahlung along the beam (and thus have wide rapidity distribution) and then boosted by transverse flow. Nontrivial correlation between directions of the jet and the radial flow is provided by jet quenching: our straightforward and basically parameter-independent calculation reproduces the angular shape, width and other properties of the "ridge".