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

TL;DR

This paper presents measurements of strange hadron production and azimuthal anisotropy at STAR BES energies, revealing insights into partonic collectivity and hadronic re-scattering effects in heavy-ion collisions.

Contribution

It provides new data on strange hadron ratios, $v_2$ scaling, and resonance production across different energies, enhancing understanding of the quark-gluon plasma.

Findings

$ ext{Lambda}/K^0_s$ ratio increases faster at 3 GeV.

NCQ scaling of $v_2$ holds for particles and anti-particles at 19.6 GeV.

$K^{*0}/K$ ratio indicates hadronic re-scattering dominates in central collisions.

Abstract

We report the production and azimuthal anisotropy measurements of strange and multi-strange hadrons at STAR BES energies. The $\Lambda/K^0_s$ 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 $K^{*0}$ resonance is also reported for 7.7-39 GeV (BES-I) and the $K^{*0}/K$ ratio suggests that hadronic re-scattering dominates over regeneration in central A+A collisions. Using the $K^{*0}/K$ ratio, we also report the lower limit of hadronic phase lifetime $( t_{kin} - t_{chem} )$.