Abstract
Background: The two-nucleon momentum distributions of nucleons and in a nucleus , is a relevant quantity that determines the probability of finding two nucleons with relative momentum and center-of-mass (c.m.) momentum ; at high values of the relative momentum and, at the same time, low values of the c.m. momentum, provides information on the short-range structure of nuclei.
Purpose: Our purpose is to calculate the momentum distributions of proton-neutron and proton-proton pairs in , and , in correspondence to various values of and .
Methods: The momentum distributions for nuclei are calculated as a function of the relative, , and center-of-mass, , momenta and relative angle , within a linked cluster many-body expansion approach, based upon realistic local two-nucleon interaction of the Argonne family and variational wave functions featuring central, tensor, and spin-isospin correlations.
Results: Independently of the mass number , at values of the relative momentum the momentum distributions exhibit the property of factorization, ; in particular, for back-to-back pairs one has , where is the deuteron momentum distribution, the c.m. motion momentum distribution of the pair, and the nuclear contact measuring the number of back-to-back pairs with deuteron-like momenta ().
Conclusions: The values of the nuclear contact are extracted from the general properties of the two-nucleon momentum distributions corresponding to . The -integrated momentum distributions exhibit the property but only at very high values of . The theoretical ratio of the momentum distributions of and and the calculated c.m. motion momentum distributions are in agreement with recent experimental data.
10 More- Received 17 July 2016
DOI:https://doi.org/10.1103/PhysRevC.94.044309
©2016 American Physical Society