Soft Contribution to the Hard Ridge in Relativistic Nuclear Collisions

TL;DR

This paper investigates the origins of the soft and hard ridge phenomena in relativistic nuclear collisions, emphasizing the role of early-stage Glasma dynamics and transverse flow in shaping observed long-range correlations.

Contribution

It extends previous work to new soft ridge measurements and quantifies the flow contribution to the hard ridge in nuclear collision data.

Findings

Soft ridge arises from early Glasma stage and flow.

Flow significantly contributes to the hard ridge.

Results enhance understanding of particle correlations in nuclear collisions.

Abstract

Nuclear collisions exhibit long-range rapidity correlations not present in proton-proton collisions. Because the correlation structure is wide in relative pseudorapidity and narrow in relative azimuthal angle, it is known as the ridge. Similar ridge structures are observed in correlations of particles associated with a jet trigger (the hard ridge) as well as correlations without a trigger (the soft ridge). Earlier we argued that the soft ridge arises when particles formed in an early Glasma stage later manifest transverse flow. We extend this study to address new soft ridge measurements. We then determine the contribution of flow to the hard ridge.