The splitting of directed flow for identified light hadrons ($K$ and $p$) and strange baryons ($\Xi$ and $\Omega$) in Au+Au collisions at STAR

Abstract

The first measurements for rapidity-odd directed flow of $\Xi$ and $\Omega$ in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=$ 27 and 200 GeV are reported. The coalescence sum rule is examined with various combinations of hadrons where all constituent quarks are produced, such as $K^{{}^{-}}(\bar{u}s)$, $\bar{p}(\bar{u}\bar{u}\bar{d})$, $\bar{\Lambda }(\bar{u}\bar{d}\bar{s})$, $\varphi (s\bar{s})$, ${\bar{\Xi }}^{+}(\bar{d}\bar{s}\bar{s})$, ${\Omega }^{-}(sss)$, and ${\bar{\Omega }}^{+}(\bar{s}\bar{s}\bar{s})$. For such combinations, a systematic violation of the sum rule is observed with increasing difference in the electric charge and the strangeness content of the combinations. Measurements are compared with the calculations of A Multi-Phase Transport (AMPT) model and Parton-Hadron String Dynamics (PHSD) model with electromagnetic (EM) field. The PHSD model with EM field agrees with the measurements within uncertainties.

Comments: Proceedings of Quark Matter 2022