Vorticity in heavy-ion collisions

We study the event-by-event generation of flow vorticity in the BNL Relativistic Heavy Ion Collider Au + Au collisions and CERN Large Hadron Collider Pb + Pb collisions by using the HIJING model. Different definitions of the vorticity field and velocity field are considered. A variety of properties of the vorticity are explored, including the impact parameter dependence, the collision energy dependence, the spatial distribution, the event-by-event fluctuation of the magnitude and azimuthal direction, and the time evolution. In addition, the spatial distribution of the flow helicity is also studied.