Radial Distribution Function for a Hard Sphere Liquid: A Modified Percus-Yevick and Hypernetted-Chain Closure Relations

Establishment of the radial distribution function by solving the Ornstein-Zernike equation is still an important problem, even more than a hundred years after the original paper publication. New strategies and approximations are common in the literature. A crucial step in this process consists in defining a closure relation which retrieves correlation functions in agreement with experiments or molecular simulations. In this paper, the functional Taylor expansion, as proposed by J. K. Percus, is applied to introduce two new closure relations: one that modifies the Percus‑Yevick closure relation and another one modifying the Hypernetted-Chain approximation. These new approximations will be applied to a hard sphere system. An improvement for the radial distribution function is observed in both cases. For some densities a greater accuracy, by a factor of five times compared to the original approximations, was obtained.

Study of the Half-Diagonal Two-Body Density Matrix of Model Nuclear Matter

The half-diagonal two-body density matrix ρ_{2h}/i(r1,r2,r') plays a central role in most theoretical treatments of the propagation of ejected nucléons and their final state interactions (FSI) in the nuclear medium. In this work based on the analysis of Ristig and Clark, we present the results of a Fermi hypernetted-chain calculation ρ_{2h}/i(r1,r2,r') for infinite symmetrical nuclear matter using a Jastrow-correlated model. The dependence of ρ_{2h} on the variables involved has been investigated in detail. Significant departures from ideal Fermi gas behavior in certain domains demonstrate the importance of short-range correlations. A comparison of our results with the predictions of Silver's approximation to ρ_{2h}, which has been employed in some treatments of FSI, reveals certain shortcomings of this approximation. The Fermi hypernetted-chain results obtained here will serve as a key input to an approximate treatment of FSI in inclusive quasielastic electron scattering from nuclear matter.

Binding energies of hypernuclei and hypernuclear interactions

In part 1 the effect of nuclear core dynamics cm the binding energies of Λ hy­ pernuclei is discussed in the framework of variational correlated wave functions. In particular, we discuss a new rearrangement energy contribution and its effect on the core polarization. In part 2 we consider the interpretation of the Λ single-particle energy in terms of basic Λ-nuclear interactions using a local density approximation based on a fermi hypernetted chain calculation of the Λ binding to nuclear matter. To account for the data strongly repulsive 3-body AN Ν forces are required. Also in this framework we discuss core polarization for medium and heavier hypernuclei.

Study of the Generalized Momentum Distribution of Model Nuclear Matter

Valuable information on the correlation structure of the nuclear medium is stored in the generalized momentum distribution n(p,Q), the Fourier transform of the half-diagonal two-body density matrix ρ_{2η}(r_1,r_2,r'). In this paper, we present a numerical calculation of n(p,Q) for two Jastrow-correlated models of symmetrical nuclear matter based on the structural decomposition of n(p,Q) derived by Ristig and Clark and on a Fermi-hypernetted-chain procedure. Results exhibit significant departures from the ideal Fermi gas case in certain kinematic domains; this behaviour indicates the strong short-range correlations present in these models. Nevertheless, such deviations are less prominent than in earlier low- cluster-order calculations. The results are also used to judge the quality of Silver's approximation for n(p,Q).