Incompressibility of hot asymmetrical nuclear matter: Lowest order constrained variational approach

The isothermal and isentropic incompressibility of asymmetrical nuclear matter are investigated in the framework of the lowest order constrained variational method. Various phenomenological nucleon-nucleon interactions, namely, the Reid, the Delta-Reid, and the new Argonne potentials are used. It is found that the temperature as well as the asymmetry parameter reduce the incompressibility of asymmetrical nuclear matter. The pressure is calculated along isentropic paths. It is shown that the equation state is much harder than the one usually assumed in the hydrodynamical simulations of supernova collapse. Various discussions are made in connection with the problem of supernova explosions and other many-body model calculations. [S0556-2813(98)03311-1].