Elliptic flow of light nuclei in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6, 19.6, 27, and 54.4 GeV using the STAR detector

TL;DR

This study measures the elliptic flow ($v_2$) of light nuclei in Au+Au collisions at various energies to investigate their production mechanisms, comparing results with nucleon $v_2$ to test the coalescence model.

Contribution

It provides experimental data on $v_2$ of light nuclei across multiple energies, testing the mass number scaling predicted by the coalescence model.

Findings

Mass number scaling of $v_2$ observed for light nuclei.

$v_2$ of light nuclei depends on transverse momentum and collision centrality.

Results support the coalescence model for light nuclei production.

Abstract

Loosely bound light nuclei are produced in abundance in heavy-ion collisions. There are two main possible models to explain their production mechanism - the thermal model and the coalescence model. The thermal model suggests that the light nuclei are produced from a thermal source, where they are in equilibrium with other species present in the fireball. However, due to the small binding energies, the produced nuclei are not likely to survive the high-temperature conditions of the fireball. The coalescence model tries to explain the production of light nuclei by assuming that they are formed at later stages by the coalescence of protons and neutrons near the kinetic freeze-out surface. The final-state coalescence of nucleons will lead to the mass number scaling of the elliptic flow ($v_2$) of light nuclei. This scaling states that the $v_2$ of light nuclei scaled by their respective mass numbers will follow very closely the $v_2$ of nucleons. Therefore, studying the $v_2$ of light nuclei and comparing it with the $v_2$ of protons will help us in understanding their production mechanism. In this talk, we will present the transverse momentum ($p_{T}$) and centrality dependence of $v_2$ of $d$, $t$, and $^3\text{He}$ in Au+Au collisions at $\sqrt{s_{NN}}$ = 14.6, 19.6, 27, and 54.4 GeV. Mass number scaling of $v_2(p_T)$ of light (anti-)nuclei will be shown and physics implications will be discussed.