Softening of the nuclear equation-of-state by kinetic non-equilibrium in heavy ion collision

Highly compressed nuclear matter created in relativistic heavy collisions is to large extent governed by local non-equilibrium. As an idealised scenario colliding nuclear matter configurations are studied with an effective in-medium interaction based on the microscopic DBHF model. It is found that on top of the repulsive momentum dependence of the nuclear forces kinetic non-equilibrium leads to an effective softening of the equation of state as compared to ground state nuclear matter. The separation of phase space which is the basic feature of such anisotropic configurations has thereby a similar influence as the introduction of a virtual new degree of freedom.