Long range rapidity correlations and jet production in high energy nuclear collisions

TL;DR

This paper investigates long-range correlations and jet production in high-energy nuclear collisions, revealing a persistent ridge structure linked to jet activity and characterizing its properties across different collision systems.

Contribution

It provides the first systematic analysis of the ridge phenomenon in high transverse momentum di-hadron correlations at RHIC, demonstrating its association with jet production in heavy-ion collisions.

Findings

Significant long-range correlations observed in Au+Au collisions.

The ridge component is weakly dependent on \\deta and persists at high \\pt.

The ridge's particle spectrum resembles bulk particle production.

Abstract

The STAR Collaboration at RHIC presents a systematic study of high transverse momentum charged di-hadron correlations at small azimuthal pair separation \dphino, in d+Au and central Au+Au collisions at $\rts = 200$ GeV. Significant correlated yield for pairs with large longitudinal separation \deta is observed in central Au+Au, in contrast to d+Au collisions. The associated yield distribution in \detano$\times$\dphi can be decomposed into a narrow jet-like peak at small angular separation which has a similar shape to that found in d+Au collisions, and a component which is narrow in \dphi and \textcolor{black}{depends only weakly on} $\deta$, the "ridge". Using two systematically independent analyses, \textcolor{black}{finite ridge yield} is found to persist for trigger $\pt > 6$ \GeVc, indicating that it is correlated with jet production. The transverse momentum spectrum of hadrons comprising the ridge is found to be similar to that of bulk particle production in the measured range ($2 < \pt < 4 \GeVc$).