Angular correlations in pA collisions from CGC: multiplicity and mean transverse momentum dependence of $v_2$

TL;DR

This paper uses the Color Glass Condensate framework to calculate azimuthal anisotropy v2 and its correlations with multiplicity and transverse momentum in pA collisions, revealing small correlations and a sharp transition linked to quantum effects.

Contribution

It introduces a detailed calculation of v2 and its correlations within the CGC approach, highlighting the impact of transverse momentum bin width on these correlations.

Findings

Correlations between v2^2 and multiplicity are very small.

A sharp change in v2^2 and correlations occurs with varying transverse momentum bin width.

The transition is linked to Bose enhancement and HBT effects.

Abstract

Within the dense-dilute Color Glass Condensate approach, and using the Golec-Biernat-Wuesthoff model for the dipole scattering amplitude, we calculate $v_2^2$ as well as the correlations between $v_2^2$ and both the total multiplicity and the mean transverse momentum of produced particles. We find that the correlations are generally very small consistent with the observations. We note an interesting sharp change in the value of $v^2_2$ as well as of its correlations as a function of the width of the transverse momentum bin. This crossover is associated with the change from Bose enhancement dominance of the correlation for narrow bin to HBT dominated correlations for larger bin width.