Vorticity and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mi mathvariant="normal">Λ</mml:mi></mml:math> polarization in the microscopic transport model PACIAE

Abstract

We study the behavior of four types of vorticities in noncentral $\text{Au}+\text{Au}$ collisions at energies $\sqrt{{S}_{NN}}=5\text{--}200$ GeV using a microscopic transport model PACIAE. The results show that the vorticities decay faster at lower energy and smaller impact parameter. The nonmonotonic dependence of the initial vorticities on the collision energies is reconfirmed and the turning point is 10--15 GeV for different vorticities. The global $\mathrm{\ensuremath{\Lambda}}$ polarization at energies $\sqrt{{S}_{NN}}=7.7\text{--}200$ GeV is reproduced by introducing an energy density freeze-out criterion.