Azimuthal harmonics of color fields in a high energy nucleus

Abstract

Recent experimental results have revealed a surprisingly rich structure of multiparticle azimuthal correlations in high energy proton–nucleus collisions. Final state collective effects can be responsible for many of the observed effects, but it has recently been argued that a part of these correlations are present already in the wavefunctions of the colliding particles. We evaluate the momentum space 2-particle cumulant azimuthal anisotropy coefficients vn{2}, n = 2, 3, 4 from fundamental representation Wilson line distributions describing the high energy nucleus. These would correspond to the flow coefficients in very forward proton–nucleus scattering. We find significant differences between Wilson lines from the MV model and from JIMWLK evolution. The magnitude and qualitative transverse momentum dependence of the vn{2} values suggest that the fluctuations present in the initial fields are a significant contribution to the observed anisotropies.