Roles of tensor and pairing correlations on halo formation inLi11

Abstract

We study the roles of the tensor and pairing correlations on the halo formation in 11 Li with an extended 9 Li+n+n model. We first solve the ground state of 9 Li in the shell model basis by taking 2p-2h states using the Gaussian functions with variational size parameters to take into account the tensor correlation fully. In 11 Li, the tensor and pairing correlations in 9 Li are Pauli-blocked by additional two neutrons, which work coherently to make the configurations containing the 0p 1/2 state pushed up and close to those containing the 1s 1/2 state. Hence, the pairing interaction works efficiently to mix the two configurations by equal amount and develop the halo structure in 11 Li. For 10 Li, the inversion phenomenon of s-and p-states is reproduced in the same framework. Our model furthermore explains the recently observed Coulomb breakup strength and charge radius for 11 Li.

Tensor-optimized shell model for the Li isotopes with a bare nucleon-nucleon interaction

“…In our previous study of 11 Li, we discuss those quantities of 11 Li in detail [25,26]. It is interesting to discuss the effect of the tensor force on these quantities in other Li isotopes using the TOSM+UCOM method.…”

“…We also see the high momentum behavior of the kinetic energy in each state in relation with the tensor correlation. The present subject of Li isotopes becomes a foundation of the nuclear structure study using TOSM+UCOM and also of the previous study of 11 Li and 10 Li structures [25,26].…”

“…Before the present analysis, for neutron-rich 10 Li and 11 Li, we have performed the coupled two-and three-body cluster model analyses assuming the 9 Li core described using the simplified TOSM wave function, respectively [6,25,26]. The cluster model for two nuclei precisely describes the neutron wave functions in a loosely bound state around 9 Li, such as a neutron halo structure in 11 Li.…”

Four-body resonances of7B using the complex scaling method

“…We explain the coupling behavior between 4 He and valence protons in COSM. This is related to the boundary condition of the proton emission in 7 B, which is important when the resonant and continuum states are treated [19,26,33]. As an example, we consider the coupling between 7 B and the 6 Be + p configurations.…”

“…In CSM, the resonant wave functions are directly obtained by diagonalization of the complex-scaled Hamiltonian using L 2 basis functions. Results for light nuclei using CSM have been obtained successfully for energies, decay widths, and spectroscopic factors, and also for breakup strengths induced by Coulomb excitations [25,26], monopole transition [21] and one-neutron removal [20]. Recently, CSM has been developed to include nuclear reaction methods such as scattering amplitude calculation [27], the Lippmann-Schwinger equation [28], and the continuum-discretized coupled-channel (CDCC) method [29].…”