Measurements of second-harmonic Fourier coefficients from azimuthal anisotropies in $p+p, p$+Au $d$+Au, and $^3$He + Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

The collaboration
Phys.Rev.C 107 (2023) 024907, 2023.

Abstract (data abstract)
Recently, the PHENIX Collaboration has published second- and third-harmonic Fourier coefficients $v_2$ and $v_3$ for midrapidity ($|\eta|<0.35$) charged hadrons in 0\%--5\% central $p$$+Au, d$$+$Au, and $^3$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV utilizing three sets of two-particle correlations for two detector combinations with different pseudorapidity acceptance [Phys. Rev. C {\bf 105}, 024901 (2022)]. This paper extends these measurements of $v_2$ to all centralities in $p$$+Au, d$$+$Au, and $^3$He$+$Au collisions, as well as $p$$+$$p$ collisions, as a function of transverse momentum ($p_T$) and event multiplicity. The kinematic dependence of $v_2$ is quantified as the ratio $R$ of $v_2$ between the two detector combinations as a function of event multiplicity for $0.5$$<$$p_T$$<$$1$ and $2$$<$$p_T$$<$$2.5$ GeV/$c$. A multiphase-transport (AMPT) model can reproduce the observed $v_2$ in most-central to midcentral $d$$+Au and ^3He+Au collisions. However, the AMPT model systematically overestimates the measurements in p$$+$$p, p$$+$Au, and peripheral $d$$+Au and ^3He+Au collisions, indicating a higher nonflow contribution in AMPT than in the experimental data. The AMPT model fails to describe the observed R for 0.5$$<$$p_T$$<$$1 GeV/c, but there is qualitative agreement with the measurements for 2$$<$$p_T$$<$$2.5$ GeV/$c$.