Alpha matter revisited
We examine in detail two alternative descriptions of a system of particles interacting via local interactions of different character, highlighting the fact that a faithful microscopic description of such systems demands a consistent treatment of both short- and long-range correlations. In preparation, we examine four different versions of modern microscopic many-body theory and conclude by emphasizing that these approaches, although {\it a priori} very different, actually lead to the same equations for their efficient application. The only quantity that depends on the formulation of many-body theory chosen is an {\it irreducible} interaction correction. In the language of Green's functions and Feynman diagrams, it is the set of both particle-particle and particle-hole irreducible diagrams, and in variational Jastrow-Feenberg theory it is determined by {\it multipartite correlations} and {\it elementary diagrams}. We apply these theoretical methods to the calculation of the energetics, structure, thermodynamics, and dynamics of matter, as well as its condensate fraction. In dimensionless units, matter appears to be remarkably similar to the much-studied He quantum fluid, its low-temperature properties now basically solved in the Jastrow-Feenberg framework. Accordingly, one can have confidence in the results of application of the same procedure to matter. Even so, closer examination reveals significant differences between the physics of the two systems. Within an infinite nuclear medium, alpha matter is subject to a spinoidal instability. Extended mixtures of nucleons and alpha particles are yet to be given rigorous consideration in a corresponding theoretical framework.