Coulomb breakup reactions of11Li in the coupled-channel9Li+n+nmodel

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 two-particle--two-hole ($2\text{p}$-$2\text{h}$) 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 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 the 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 are hardly confirmed in the spectra.