Spin alignment of vector mesons from quark dynamics in a rotating medium

Abstract

Vorticities in heavy-ion collisions (HICs) are supposed to induce spin alignment and polarization phenomena of quarks and mesons. In this work, we analyze the spin alignment of vector mesons $\varphi$ and $\rho$ induced by rotation from quark dynamics in the framework of the Nambu-Jona-Lasinio (NJL) model. The rotating angular velocity induces mass splitting of spin components for vector $\varphi ,\rho$ mesons $M_{\varphi ,\rho }(\Omega )\simeq M_{\varphi ,\rho }(\Omega =0)-s_z\Omega$. This behavior contributes to the spin alignment of vector mesons $\varphi ,\rho$ in an equilibrium medium and naturally explains the negative deviation of ${\rho }_{00}-1/3$ for vector mesons. Incidentally, the positive deviation of ${\rho }_{00}-1/3$ under the magnetic field can also be easily understood from quark dynamics.

Comments: 12 pages, 8 figures