Study of the effect of the tensor correlation in oxygen isotopes with the charge- and parity-projected Hartree-Fock method

Recently, we developed a mean-field-type framework that treats the correlation induced by the tensor force. We treat the tensor correlation by introducing intrinsic single-particle states with parity and charge mixing. We make a total wave function with definite charge number and good parity by performing the charge number and parity projections. Taking a variation of the total energy calculated with the projected wave function, we obtain a Hartree-Fock-like equation (charge- and parity-projected Hartree-Fock equation). We extend further the charge- and parity-projected Hartree-Fock method to include a three-body force, which is important to reproduce the saturation property of nuclei in a mean-field framework. We apply the charge- and parity-projected Hartree-Fock method to sub-closed-shell oxygen isotopes (¹⁴O, ¹⁶O, ²²O, ²⁴O, and ²⁸O) to study the effect of the tensor correlation and its dependence on neutron number. We obtain reasonable binding energies and matter radii for these nuclei. It is found that relatively large energy gains come from the tensor force in these isotopes and further the blocking effect on the tensor correlation arises due to additional neutrons.