Local spin polarization of $\Lambda$ hyperons and its interaction corrections

Abstract

We have computed the second Fourier sine coefficient of the longitudinal spin polarization, $⟨P_z\sin 2({\varphi }_p-{\Psi }_2)⟩$, as a function of multiplicity or centrality in Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV and in $p$+Pb collisions at $\sqrt{s_{NN}}=8.16$ TeV using the CLVisc hydrodynamic framework. The numerical results successfully describe the data in Au+Au collisions. However, understanding the data in $p$+Pb collisions remains a puzzle. Additionally, we have reported some recent developments in quantum kinetic theory and spin hydrodynamics.

Comments: 6 pages, 2 figures. Contribution to the proceedings of Quark Matter 2025