CGC/saturation approach for high energy soft interactions: `soft' Pomeron structure and $v_{n}$ in hadron and nucleus collisions from Bose-Einstein correlation

TL;DR

This paper models high-energy soft interactions using the CGC/saturation approach, showing that Bose-Einstein correlations of gluons significantly influence flow coefficients $v_n$, aligning with experimental data and challenging hydrodynamic interpretations.

Contribution

It introduces a model linking Bose-Einstein correlations and the structure of the dressed Pomeron to observed flow coefficients in various collision systems.

Findings

$v_n$ values are close to experimental data for proton-proton collisions.

$p$-Pb collisions show $v_n$ values 20% smaller than observed.

$v_n$ in Pb-Pb collisions matches data for central collisions.

Abstract

In the framework of our model of soft interactions at high energy based on CGC/saturation approach,we show that Bose-Einstein correlations of identical gluons lead to large values of $v_n$. We demonstrate how three dimensional scales of high energy interactions: hadron radius, typical size of the wave function in diffractive production of small masses (size of the constituent quark), and the saturation momentum, influence the values of BE correlations, and in particular, the values of $v_n$. Our calculation shows that the structure of the `dressed' Pomeron leads to values of $v_n$ which are close to experimental values for proton-proton scattering, 20\% smaller than the observed values for proton-lead collisions, and close to lead-lead collisions for 0-10\% centrality. Bearing this result in mind, we conclude that it is premature to consider, that the appearance of long range rapidity azimuthal correlations are due only to the hydrodynamical behaviour of the quark-gluon plasma.