Antiflow of nucleons at the softest point of the equation of state

Abstract

We investigate flow in semiperipheral nuclear collisions at Alternating Gradient Synchrotron and Super Proton Synchrotron energies within macroscopic as well as microscopic transport models. The hot and dense zone assumes the shape of an ellipsoid which is tilted by an angle $\ensuremath{\Theta}$ with respect to the beam axis. If matter is close to the softest point of the equation of state, this ellipsoid expands predominantly orthogonal to the direction given by $\ensuremath{\Theta}.$ This antiflow component is responsible for the previously predicted reduction of the directed transverse momentum around the softest point of the equation of state.