Polarization of $\lambda$-hyperons, vorticity and helicity structure in heavy-ion collisions

Simulations of peripheral Au+Au collisions at NICA energies are performed in the PHSD transport model. The properties of velocity and vorticity fields as well as hydrodynamic helicity are studied at different impact parameters and energies. A general structure of the velocity field follows the “little bang” pattern which may be quantified by the velocity dependence allowing to extract the “Hubble” constant. A quadrupole-like structure of the vorticity field in all the planes is obtained. The helicity-separation effect is found. Calculations of the Λ-hyperon polarization is performed within the thermodynamic and anomalous models at NICA energies.