Production yield and azimuthal anisotropy measurements of strange hadrons from BES at STAR

Abstract

We report the production and azimuthal anisotropy measurements of strange and multi-strange hadrons at STAR BES energies. The $\Lambda /K_s^0$ ratio is reported at 3 GeV and observed to increase faster with transverse momentum than that at higher energies. The number-of-constituent quark (NCQ) scaling of $v_2$ has been studied at 19.6 GeV (BES-II). The NCQ scaling holds for particles and anti-particles, which can be considered as an evidence of partonic collectivity. The production of $K^{\ast 0}$ resonance is also reported for 7.7-39 GeV (BES-I) and the $K^{\ast 0}/K$ ratio suggests that hadronic re-scattering dominates over regeneration in central A+A collisions. Using the $K^{\ast 0}/K$ ratio, we also report the lower limit of hadronic phase lifetime $(t_{kin}-t_{chem})$.