Coulomb breakup reactions of $^{11}$Li in the coupled-channel $^9$Li~+~$n$~+~$n$ three-body model

TL;DR

This study models the Coulomb breakup of the two-neutron halo nucleus $^{11}$Li using a coupled-channel three-body approach, successfully reproducing experimental data and revealing the significance of s-state mixing and virtual states in the breakup process.

Contribution

It introduces a coupled-channel three-body model incorporating tensor and pairing correlations, providing new insights into the breakup mechanism of $^{11}$Li and the role of virtual states.

Findings

Breakup cross section matches experimental results.

Large s-state mixing influences the shape and strength of the cross section.

Virtual s-states significantly contribute to low-lying peaks in invariant mass spectra.

Abstract

We investigate the three-body Coulomb breakup of a two-neutron halo nucleus $^{11}$Li. We use the coupled-channel $^9$Li + $n$ + $n$ three-body model, which includes the coupling between last neutron states and the various $2p$-$2h$ configurations in $^9$Li due to the tensor and pairing correlations. The three-body scattering states of $^{11}$Li are described by using the combined methods of the complex scaling and the Lippmann-Schwinger equation. The calculated breakup cross section successfully reproduces the experiments. The large mixing of the s-state in the halo ground state of $^{11}$Li is shown to play an important role in explanation of shape and strength of the breakup cross section. In addition, we predict the invariant mass spectra for binary subsystems of $^{11}$Li. It is found that the two kinds of virtual s-states of $^9$Li-$n$ and $n$-$n$ systems in the final three-body states of $^{11}$Li largely contribute to make low-lying peaks in the invariant mass spectra. On the other hand, in the present analysis, it is suggested that the contributions of the p-wave resonances of $^{10}$Li is hardly confirmed in the spectra.