New Properties of High Momentum Distribution of Nucleons in Asymmetric Nuclei

TL;DR

This paper proposes new properties of high-momentum nucleon distributions in asymmetric nuclei, highlighting scaling relations and inverse proportionalities, and models these distributions to explain experimental observations, especially in neutron-rich heavy nuclei.

Contribution

It introduces two novel properties of high-momentum distributions in asymmetric nuclei and models these to match experimental data, revealing unexpected proton abundance in neutron-rich nuclei.

Findings

High-momentum distributions follow a scaling relation between protons and neutrons.

Inverse proportionality exists between distribution strength and relative fractions.

In neutron-rich nuclei like gold, protons can be more abundant at high momenta.

Abstract

Based on the recent experimental observations of the dominance of tensor interaction in the ~250-600~MeV/c momentum range of nucleons in nuclei, the existence of two new properties for high-momentum distribution of nucleons in asymmetric nuclei is suggested. The first property is the approximate scaling relation between proton and neutron high-momentum distributions weighted by their relative fractions in the nucleus. The second property is the inverse proportionality of the strength of the high-momentum distribution of protons and neutrons to the same relative fractions. Based on these two properties the high-momentum distribution function for asymmetric nuclei has been modeled and demonstrated that it describes reasonably well the high-momentum characteristics of light nuclei. However, the most surprising result is obtained for neutron rich nuclei with large A, for which a substantial relative abundance of high-momentum protons as compared to neutrons is predicted. For example, the model predicts that in Au the relative fraction of protons with momenta above $k_{F} \sim 260$~MeV/c is 50% more than that of neutrons. Such a situation may have many implications for different observations in nuclear physics related to the properties of a proton in neutron rich nuclei.