NATURAL ORBITALS, OVERLAP FUNCTIONS, AND MEAN-FIELD ORBITALS IN AN EXACTLY SOLVABLE A-BODY SYSTEM

consider a simple but nontrivial many-body system interacting through short-range forces, and confirm a property of such systems that was re cently proposed on general grounds, namely, that single-particle overl ap functions, spectroscopic factors, and separation energies of the bo und (A-1)-particle eigenstates can be derived from the one-body densit y matrix of the A-particle system in its ground state. The basis of na tural orbitals for the system is constructed and its properties are di scussed. We also investigate the high-momentum content of the bound-st ate overlap functions and momentum distribution. It is found that the mean field provides a good approximation for the bound-state overlap f unctions even in the region of large momenta, where the total momentum distribution is already enhanced by several orders of magnitude over the mean-field result.