Exploring correlations in the CGC wave function: odd azimuthal anisotropy

TL;DR

This paper extends the CGC framework to include high-density effects in the projectile wave function, revealing the emergence of odd azimuthal anisotropies in two-particle correlations, with potential experimental signatures.

Contribution

It introduces high-density effects into the CGC approach, demonstrating their role in generating odd harmonics in gluon correlations, a novel insight in the field.

Findings

High-density effects produce positive c_1{2} at high momenta.

Density effects generate positive c_3{2} when |k|/|p| ~ 1.

Sign of c_3{2} changes when |k|/|p| > 1.1.

Abstract

We extend the CGC approach to calculation of the double inclusive gluon production by including high-density effect in the CGC wave function of the projectile (proton). Our main result is that these effects lead to the appearance of odd harmonics in the two-particle correlation C(k,p). We find that in the high momentum limit, |k|,|p|>>Q_s, this results in a positive c_1{2}. Additionally when the magnitudes of the two momenta are approximately equal, |k|/|p| ~ 1, the density effects also generate a positive third harmonic c_3{2}, which translates into a non-vanishing v_3 when the momenta of the trigger and associated particle are in the same momentum bin. The sign of c_3{2} becomes negative when |k|/|p|>1.1 suggesting an interesting experimental signature.