Detailed study of the cluster structure of light nuclei in a three-body model (IV). Large space calculation for A = 6 nuclei with realistic nuclear forces☆

A realistic three-body model of 6Li with local interactions

For pt.I see ibid., vol.8, no.5, p.667-78 (1982). The variational approach to calculations of multicluster systems which was developed in part I, is applied to a study of low-lying states with Jpi T=1+0 and 0+1 in nuclei with A=6. The interaction Hamiltonian includes the central spin-orbit and tensor forces. The effect of the Pauli principle is included through the requirement of orthogonality of the total wavefunction to the forbidden OS state in the n- alpha and p- alpha subsystems. The Coulomb interaction is included accurately. The P-component admixtures to the total wavefunction are studied. The value of the mathematical expectation of the 6Li Hamiltonian is shown to be relatively insensitive to the P-component contribution. The character of saturation in the pseudo-potential coupling constant corresponding to the contribution of the forbidden states is studied. The calculated Coulomb differences for the 6He-6Li-6Be isobaric triplet prove to be in rather good agreement with the experimental data, as are the value of the RMS radius and the behaviour of the charge form factor of the 6Li ground state.

A variational study of the ground and excited states of light nuclei in a three-body model on the complete basis. II. The structure of 6He-6Li-6Be nuclei in the α+2N model

ΛΛ6He as a ΛΛ interaction constraint

The Nijmegen OBE potential D is SU(3) rotated to model the strangeness -2 sector of the baryon-baryon force Soft core repulsion is introduced to regularize the singular nature of the OBE functions The strength of the $^1$S$_0$ $t=0$ interaction is adjusted to model three scenarios: (1) a bound state, (2) a narrow virtual, or antibound, state, and (3) an unbound state in which the force is weakly attractive Using a separable approximation to these potentials, the binding energy of $^{6}_{\Lambda\Lambda}$He is calculated in an $\Lambda\Lambda\alpha$ model The resultant binding energies suggest that the strength of the $^1$S$_0$ $t=0$ $\Lambda\Lambda$ and the $nn$ interactions should be similar, if the coupling between the $\Lambda\Lambda$ and $\Xi N$ channels is taken into consideration

$^{6}_{\Lambda\Lambda}$He as a $\Lambda\Lambda$ interaction constraint

Separable-potential three-body (..cap alpha..np) models of the /sup 6/Li ground state are examined. Different separable-potential fits to the ..cap alpha..-n phase shifts and the low-energy /sup 3/S/sub 1/-/sup 3/D/sub 1/ two-nucleon parameters are reviewed, after which integral equations are derived for the spectator functions of the /sup 6/Li ground-state wave function assuming S/sub 1/2/, P/sub 1/2/, and P3/2 components in the ..cap alpha..-n interaction. These equations are solved to determine the /sup 6/Li binding energy and investigate its sensitivity to the /sup 3/D/sub 1/ component of the two-nucleon interaction, its variation upon neglecting different components of the ..cap alpha..-n interaction, and its dependence on different analytical forms for the P-wave ..cap alpha..-n interactions. For two wave functions derived from the same set of ..cap alpha..-n interactions, but with the /sup 3/S/sub 1/-/sup 3/D/sub 1/ two-nucleon interaction producing 0% and 4% d-wave components in the deuteron, respectively, the spectator functions are given and the contributions to the ground-state normalization of the various components are calculated. The latter two wave functions correspond to three-body /sup 6/Li binding energies of 4.446 MeV (0%) and 4.070 MeV (4%) compared with the Coulomb-adjusted experimental value of 4.53 MeV.

Mamta Rai

Papers

Separable-potential three-body model of the A = 6 system. II. /sup 6/Li ground state

Alpha-deuteron structure of 6Li as predicted by a separable-potential three-body model