Evolution of structures in two particle correlations in RHIC Cu+Cu collisions as a function of centrality and momentum

TL;DR

This paper investigates how the 'ridge' phenomenon in two-particle correlations in Cu+Cu collisions at RHIC varies with collision centrality and particle momentum, providing insights into its possible origins.

Contribution

It presents a detailed analysis of the momentum and centrality dependence of the ridge in Cu+Cu collisions, highlighting how correlation parameters change with these variables.

Findings

Correlation amplitude varies with centrality and momentum cut-off.

Widths of the near side correlation depend on collision centrality.

Implications discussed for the origin of the ridge phenomenon.

Abstract

Two particle correlation measurements in heavy ion collisions at RHIC have shown an extended near side correlation in $\Delta\eta$ relative to p+p for both, momentum triggered and untriggered analyses. This phenomenon is also known as the "ridge". An investigation into the momentum and centrality dependence of two particle correlations is presented for Cu+Cu 200 GeV collisions from the STAR experiment. We extract the amplitude, $\Delta\eta$ and $\Delta\phi$ widths from the near side correlation structure, and show how its parameters depend on centrality and the lower transverse momentum cut-off. Implications for the origin of the ridge will be discussed.