Angular momentum conservation in heavy ion collisions at very high energy

Understand

The effects of angular momentum conservation in peripheral heavy ion collisions at very high energy are investigated.

• It is shown that the initial angular momentum of the quark-gluon plasma should enhance the azimuthal anisotropy of particle spectra (elliptic flow) with respect to the usual picture where only the initial geometrical eccentricity of the nuclear overlap region is responsible for the anisotropy.
• In hydrodynamical terms, the initial angular momentum entails a non trivial dependence of the initial longitudinal flow velocity on the transverse coordinates.
• This gives rise to a non-vanishing vorticity in the equations of motion which enhances the expansion rate of the supposedly created fluid compensating for the possible quenching effect of viscosity.