Phase-space distributions of nuclear short-range correlations

TL;DR

This paper investigates how nuclear short-range correlations (SRCs) affect phase-space distributions in nuclei, revealing their localization in the interior and their impact on kinetic energy, radius, and neutron skin in various nuclei.

Contribution

It introduces a phase-space analysis of SRCs using Wigner distributions and quantifies their effects on nuclear properties across different nuclei.

Findings

SRCs significantly increase kinetic energy, especially in the nuclear interior.

SRCs induce high-momentum components confined to the nuclear interior.

SRCs reduce the neutron skin of $^{48}$Ca by up to 10%.

Abstract

Nuclear short-range correlations (SRCs) induce high-momentum/high-energy fluctuations in the nuclear medium. In order to assess their impact on nuclear bulk properties, like nuclear radii and kinetic energies, it is instrumental to determine how SRCs are distributed in phase space as this sheds light on the connection between their appearance in coordinate and momentum space. Using the lowest-order correlation operator approximation (LCA) to include SRC, we compute two-dimensional nuclear Wigner quasiprobability distributions $w(r, k)$ to locate those $({r}, {k})$ phase-space regions that are most heavily impacted by SRCs. The SRC-induced high-momentum components find their origin in a radial range that is confined to the nuclear interior. Significant SRCs strength is generated in the full momentum range $0 \leq k \lesssim 5 ~\text{fm}^{-1} $ covered in this work, but below the Fermi momentum those are dwarfed by the mean-field contributions. As an application of $w(r, k)$, we focus on the radial dependence of the kinetic energy $T$ and the momentum dependence of the radius $r_{\text{rms}}$ for the symmetric nuclei $^{12}$C, $^{40}$Ca and the asymmetric nucleus $^{48}$Ca. The kinetic energy almost doubles after including SRCs, with the largest increase occurring in the nuclear interior $r \lesssim 2$ fm. The momentum dependence of the $r_{\text{rms}}$ teaches that the largest contributions stem from $k \lesssim 2 $ fm$^{-1}$, where the SRCs induce a slight reduction of the order of a few percent. The SRCs systematically reduce the $^{48}$Ca neutron skin by an amount that can be 10\%.