Global polarization of $\Lambda$ and $\bar{\Lambda }$ hyperons in Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}=19.6$ and $27$ GeV

The STAR Collaboration

In relativistic heavy-ion collisions, a global spin polarization, $P_{\mathrm{H}}$, of $\Lambda$ and $\bar{\Lambda }$ hyperons along the direction of the system angular momentum was discovered and…