Measurements of strange and multi-strange hadrons elliptic flow in isobar collisions at RHIC by STAR

Abstract

We present measurements of elliptic flow ($v_{2}$) of $K_{s}^{0}$, $Λ$, $\barΛ$, $φ$, $Ξ^{-}$, $\overlineΞ^{+}$, and $Ω^{-}$+$\overlineΩ^{+}$ at mid-rapidity ($|η| <$ 1.0) in isobar collisions ($^{96}_{44}$Ru+$^{96}_{44}$Ru and $^{96}_{40}$Zr+$^{96}_{40}$Zr) at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV. The centrality and transverse momentum ($p_{\mathrm{T}}$) dependence of elliptic flow is presented. The number of constituent quark (NCQ) scaling of $v_{2}$ in isobar collisions is discussed. $p_{T}$-integrated elliptic flow ($\left\langle v_{2}\right\rangle$) is observed to increase from central to peripheral collisions. The ratio of $\left\langle v_{2}\right\rangle$ between the two isobars shows a deviation from unity for strange hadrons ($K_{s}^{0}$, $Λ$ and $\barΛ$) indicating a difference in nuclear structure and deformation. A system size dependence of strange hadron $v_{2}$ at high $p_{T}$ is observed among Ru+Ru, Zr+Zr, Cu+Cu, Au+Au, and U+U systems. A multi-phase transport (AMPT) model with string melting (SM) describes the experimental data well in the measured $p_{\mathrm{T}}$ range for isobar collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV.