Two-neutron correlations in microscopic wave functions of He-6, He-8 and C-12

TL;DR

This paper investigates two-neutron correlations in microscopic wave functions of helium isotopes and carbon-12, revealing surface-enhanced di-neutron correlations and emphasizing the importance of configuration mixing.

Contribution

It provides a detailed analysis of di-neutron correlations in helium isotopes and carbon-12 using microscopic wave functions, highlighting the role of configuration mixing.

Findings

Surface enhancement of di-neutron correlations in He-6 and He-8

Significant di-neutron correlation in He-6 ground state

Configuration mixing is essential for accurate di-neutron description

Abstract

Two-neutron densities obtained from microscopic wave functions of $^6$He and $^8$He are investigated to reveal di-neutron correlations. In particular, the comparison of the two-neutron density with the product of one-neutron densities is useful for a quantitative discussion of di-neutron correlations. The calculations show that the S=0 spatial two-neutron correlation increases at the surface of $^6$He$(0^+_1)$ and $^8$He$(0^+_2)$. The enhancement is remarkable in the $^6$He$(0^+_1)$ ground state but not as prominent in the $^8$He$(0^+_1)$ ground state. Configuration mixing of many Slater determinants is essential to describe the di-neutron correlations. Two-neutron densities in $^{12}$C wave functions with $\alpha$-cluster structures are also studied.