Speaker
Description
In non-central heavy ion collisions, large angular momentum is generated, leading to the creation of significant vorticity and subsequent spin polarization of particles with finite spin. The global polarization of $\Lambda$ hyperons ($P_\Lambda$) measured along the direction of global angular momentum can serve as an effective probe of vorticity as well as spin degrees of freedom. Recently, global $\Lambda$ polarization has been measured over a wide collision energy range. The Fixed-Target program at the STAR experiment at RHIC provides a unique opportunity to study $P_\Lambda$ in regions of high baryon density.
In this talk, we report the measurements of global $\Lambda$ polarization, at $\sqrt{s_{NN}} = 3.0, 3.2, 3.5, 3.9$ and $4.5$ GeV in fixed-target Au+Au collisions. The dependence on collision energy, centrality, rapidity and transverse momentum of the measured $P_{\Lambda}$ will be discussed.
