Hadron Correlations Measured with ALICE

TL;DR

This paper reports on two-particle angular correlations measured with ALICE in heavy-ion collisions, revealing a broadening of the near-side peak in pseudorapidity and differences in particle composition suggestive of jet fragmentation effects.

Contribution

First measurement of two-particle angular correlations with identified particles in heavy-ion collisions using ALICE, highlighting the broadening of the near-side peak in pseudorapidity and particle composition insights.

Findings

Broadening of the near-side peak in η-direction from peripheral to central collisions.

The p/π ratio of associated particles is smaller than in the bulk, consistent with vacuum fragmentation.

The rms of the near-side peak in φ-direction is independent of centrality.

Abstract

Angular particle correlations are a powerful tool to study collective effects and in-medium jet modification as well as their interplay in the hot and dense medium produced in central heavy-ion collisions. We present measurements of two-particle angular correlations of inclusive charged and identified particles performed with the ALICE detector. The near-side peak in the short-range correlation region is quantitatively analyzed: while the rms of the peak in $\phi$-direction is independent of centrality within uncertainties, we find a significant broadening in $\eta$-direction from peripheral to central collisions. The particle content of the near-side peak is studied finding that the $p/\pi$ ratio of particles associated to a trigger particle is much smaller than the one in the bulk of the particles and consistent with fragmentation of a parton in vacuum.