Speaker
Description
Azimuthal anisotropies are sensitive observables to the initial stage of heavy-ion collisions. Strange and multi-strange hadrons are suitable candidates to measure these flow coefficients due to their small hadronic interaction cross section and early freezeout from the medium. Earlier in beam energy scan phase-I (BES-I), STAR collaboration measured the rapidity-odd directed flow for $\Lambda$, $\bar{\Lambda}$, $K^{\pm}$, $K_{S}^{0}$, and $\phi$ at $\sqrt{s_{NN}}$ = 7.7 - 200 GeV. The $v_{1}$ slope ($dv/dy$) at mid-rapidity shows a minimum value for the net-proton and net-$\Lambda$ when the collision energy is around 10-20 GeV which may be related to a signature of the first-order phase transition in the QCD phase diagram. It has been observed that $v_{2}$ of $\phi$ mesons shows quite different trend at $\sqrt{s_{NN}}$ = 7.7 and 11.5 GeV compared to other charged hadrons. The NCQ scaling also fails at these low energies for $\phi$ mesons and other anti-baryons which may indicate different hadron formation mechanism at these low energies. Due to less statistics, it was difficult to make any quantitative conclusion. %High statistics measurements are required to confirm the $v_{2}$ trend of $\phi$ mesons as well as validity of the NCQ scaling at low energies.
The STAR experiment has finished the data taking of BES-II program in 2021 with improved detector conditions. In this poster, we will present the high statistics measurements of $v_{1}(y)$ and $v_{2}(p_{T})$ for $K_{S}^{0}$, $\Lambda$, $\bar{\Lambda}$, $\Xi^{-}$, $\bar{\Xi}^{+}$, $\phi$, $\Omega^{-}$, and $\bar{\Omega}^{+}$ at $\sqrt{s_{NN}}$ = 3, 7.7, 14.6, and 19.6 GeV. The centrality dependence of $v_{2}$ and NCQ scaling will be shown for all the particles.
