Improved quark coalescence model for spin alignment and polarization of hadrons

Abstract

We propose an improved quark coalescence model for spin alignment of vector mesons and polarization of baryons by spin density matrix with phase space dependence. The spin density matrix is defined through Wigner functions. Within the model we propose an understanding of spin alignments of vector mesons $\varphi$ and $K^{\ast 0}$ (including ${\bar{K}}^{\ast 0}$) in the static limit: a large positive deviation of ${\rho }_{00}$ for $\varphi$ mesons from 1/3 may come from the electric part of the vector $\varphi$ field, while a negative deviation of ${\rho }_{00}$ for $K^{\ast 0}$ may come from the electric part of vorticity tensor fields. Such a negative contribution to ${\rho }_{00}$ for $K^{\ast 0}$ mesons, in comparison with the same contribution to ${\rho }_{00}$ for $\varphi$ mesons which is less important, is amplified by a factor of the mass ratio of strange to light quark times the ratio of $⟨{\mathbf{p}}_b^2⟩$ on the wave function of $K^{\ast 0}$ to $\varphi$ (${\mathbf{p}}_b$ is the relative momentum of two constituent quarks of $K^{\ast 0}$ and $\varphi$). These results should be tested by a detailed and comprehensive simulation of vorticity tensor fields and vector meson fields in heavy ion collisions.

RevTex 4, 20 pages, 3 figures, with minor changes, to appear in PRD

References in corpus (7)

• Angular momentum conservation in heavy ion collisions at very high energy
• Polarization probes of vorticity in heavy ion collisions
• Collective longitudinal polarization in relativistic heavy-ion collisions at very high energy
• Global quark polarization in non-central $A+A$ collisions
• Global $\Lambda$ Polarization in high energy collisions
• Flow Vorticity in Peripheral High Energy Heavy Ion Collisions
• Mass Correction to Chiral Kinetic Equations

Cited by in corpus (4)

• A hydrodynamic study of hyperon spin polarization in relativistic heavy ion collisions
• Spin alignment measurement of vector mesons produced in high energy collisions
• Space-average electromagnetic fields and EM anomaly weighted by energy density in heavy-ion collisions
• Helicity polarization in relativistic heavy ion collisions