A solvable model for spin polarizations with flow-momentum correspondence

We present an analytically solvable model based on the blast-wave picture of heavy-ion collisions with flow-momentum correspondence. It can describe the key features of spin polarizations in heavy-ion collisions. With the analytical solution, we can clearly show that the spin polarization with respect to the reaction plane is governed by the directed flow, while the spin polarization along the beam direction is governed by the ellipticity in flow and in transverse emission area. There is a symmetry between the contribution from the vorticity and from the shear stress tensor due to the flow-momentum correspondence. The solution can be improved systematically by perturbation method.