Measurements of the elliptic and triangular azimuthal anisotropies in central $^{3}$He+Au, $d$+Au and $p$+Au collisions at $\mbox{$\sqrt{s_{\mathrm{NN}}}$}$ = 200 GeV

TL;DR

This study measures elliptic and triangular azimuthal anisotropies in small collision systems at 200 GeV, revealing system-dependent $v_2$ and system-independent $v_3$, which inform hydrodynamic models of these systems.

Contribution

It provides the first detailed measurements of $v_2$ and $v_3$ in $^{3}$He+Au, $d$+Au, and $p$+Au collisions at 200 GeV, highlighting the role of sub-nucleonic fluctuations.

Findings

$v_2$ depends on the colliding system.

$v_3$ is system-independent within uncertainties.

Results constrain hydrodynamic models.

Abstract

The elliptic ($v_2$) and triangular ($v_3$) azimuthal anisotropy coefficients in central $^{3}$He+Au, $d$+Au, and $p$+Au collisions at $\mbox{$\sqrt{s_{\mathrm{NN}}}$}$ = 200 GeV are measured as a function of transverse momentum ($p_{\mathrm{T}}$) at mid-rapidity ($|\eta|<$0.9), via the azimuthal angular correlation between two particles both at $|\eta|<$0.9. While the $v_2(p_{\mathrm{T}})$ values depend on the colliding systems, the $v_3(p_{\mathrm{T}})$ values are system-independent within the uncertainties, suggesting an influence on eccentricity from sub-nucleonic fluctuations in these small-sized systems. These results also provide stringent constraints for the hydrodynamic modeling of these systems.