Probing the sensitivity of anisotropic flow coefficients to the initial nuclear structure in pO and OO collisions at the LHC

TL;DR

This paper investigates how the internal clustered structure of oxygen nuclei affects anisotropic flow in small collision systems at the LHC, revealing significant effects in oxygen-oxygen collisions but minimal in proton-oxygen.

Contribution

It presents the first study of anisotropic flow coefficients in pO and OO collisions using a hybrid hydrodynamics model with clustered nuclear geometry considerations.

Findings

Clustering effects are significant in OO collisions.

Effect of alpha-clustering in pO is small.

Flow coefficients depend on the size of the helium clusters.

Abstract

RHIC and LHC have injected $^{16}\rm O$ nuclei in their accelerator complexes with a focus on investigating collectivity and the origin of quark-gluon plasma signatures in small collision systems. The $^{16}\rm O$ nuclei are known to possess clusters of $\alpha$-particles ($^{4}\rm He$) inside the nucleus. This paper attempts to study the clustered-nuclear-geometry dependence of anisotropic flow coefficients such as elliptic flow ($v_2$) and triangular flow ($v_3$), which are sensitive to the nuclear geometry of colliding nuclei. The study is performed in pO and OO collisions at $\sqrt{s_{\rm NN}}=9.61$~TeV and 7~TeV respectively, employing a hybrid model encompassing IP-Glasma + MUSIC + iSS + UrQMD. The results of the clustered nuclear geometry are compared with those of the Woods\,--\,Saxon nuclear profile. Both initial and final state anisotropies are estimated. This study is thus one of its first kind, where the study of anisotropic flow coefficients for pO and OO collisions is presented using a hybrid hydrodynamics model. While the effect of $\alpha$-clustering in pO is found to be small, it is significant for each observable studied in OO collisions. It is also observed that the magnitude of this effect has a noteworthy dependence on the size of the \textsuperscript{4}He.