Equation of State at Densities Greater than Nuclear Density

An equation of state is developed for densities from nuclear density (3 x 1014 g cm−3) to about 1016 g cm−3. The repulsive interaction between baryons dominates and empirical arguments for its existence are given. This interaction is attributed to vector meson exchange, and is derived from classical field theory whereupon a Yukawa potential results. The potential actually assumed is a modification of the Reid potential. Arguments are given that the baryons will not form a crystal lattice. The actual calculations were done using Pandharipande's method. The particles present at high density certainly include nucleons, Λ and Σ. The presence of Δ is questionable but that of π is likely. Results are given for the concentration of various species. With the more likely assumption about interactions, the concentration of each permissible species of particle is about equal at ϱ = 1016 g cm−3. The relation between energy and density is nearly independent of the assumptions on the species permitted and the energy is about 3 GeV particle−1 at ϱ = 1016 g cm−3. The relation between pressure and energy density is given, which yields a sound velocity equal to c at a few times 1015 g cm−3. Results for the structure of neutron stars are given. The maximum mass is about 2 solar masses and the maximum moment of inertia 1045 g cm2.