GROUND-STATE ENERGY OF A HARD-SPHERE FERMI FLUID .2. SPIN AND ISOSPIN

We evaluate the fourth-order Hugenholtz diagrams from the Rayleigh-Sch rodinger many-body perturbation series for a repulsive, square-well po tential. We consider a system containing four different equal-mass ide ntically interacting particle species, similar to nuclear matter when only the repulsive core is considered. We use the results of these cal culations to extend the L expansion of the ground-state energy of a Fe rmi fluid by one more term. From this extension, we are able to provid e accurate values of the ground-state energy over a density range whic h includes that for infinite nuclear matter.