# Quark Matter 2018

13-19 May 2018
Venice, Italy
Europe/Zurich timezone
The organisers warmly thank all participants for such a lively QM2018! See you in China in 2019!

## Multi-particle correlations and collectivity in $pA$ collisions from an initial state parton model

15 May 2018, 15:20
20m
Sala Mosaici-1, 3rd Floor (Palazzo del Casinò)

### Sala Mosaici-1, 3rd Floor

#### Palazzo del Casinò

Parallel Talk Collectivity in small systems

### Speaker

Mark Mace (Stony Brook University)

### Description

We report on recent progress in understanding multi-particle correlations in $pA$ collisions from the initial state. We consider a proof of principle model of eikonal quarks from the projectile proton multiple-scattering off of a dense nuclear target. With this model, we find that many of the features observed in light-heavy ion collisions at RHIC and the LHC which are often ascribed to collectivity can be qualitatively reproduced in an initial state model. These include the ordering of the two-particle azimuthal angle n-th Fourier harmonics, $v_n\{2\}$; a negative four-particle second Fourier cumulant $c_2\{4\}$, giving rise to a real $v_2\{4\}$; the energy and transverse momentum dependence of $v_2\{4\}$; the similarity in multi-particle second Fourier harmonics $v_2\{4\} \approx v_2\{6\} \approx v_2\{8\}$; and the energy dependence of the four-particle symmetric cumulants. Finally, we consider the Glasma graph approximation of our model and find that many of these features cannot be reproduced, leading to the conclusion that multiple-scattering is a key ingredient for the observed multi-particle correlations from the initial state.

[1] K. Dusling, M. Mace, R. Venugopalan. Multiparticle collectivity from initial state correlations in high energy proton-nucleus collisions. arXiv:1705.00745 [hep-ph]
[2] K. Dusling, M. Mace, R. Venugopalan. Parton model description of multiparticle azimuthal correlations in pA collisions. arXiv:1706.06260 [hep-ph]

Content type Theory Presenter name already specified

### Primary author

Mark Mace (Stony Brook University)

### Co-authors

Kevin Dusling (Physical Review Letters) Raju Venugopalan (Brookhaven National Laboratory)