Proton-neutron pairing and binding energies of nuclei close to the N = Z line

We analyze the contribution of isovector and isoscalar proton-neutron pairing to the binding energies of even-even nuclei with N - Z = 0, 2, 4 and atomic mass 20 < A < 100. The binding energies are calculated in the mean-field approach by coupling a Skyrme-type functional to an isovector-isoscalar pairing force of zero range. The latter is treated in the framework of quartet condensation model (QCM), which conserves exactly the particle number and the isospin. The interdependence of pairing and deformation is taken into account by performing self-consistent Skyrme-HF + QCM calculations in the intrinsic system. It is shown that the binding energies are not changing much when the isoscalar pairing is switched on. This fact is related to the off-diagonal matrix elements of the pairing force, which are less attractive for the isoscalar force, and to the competition between the isoscalar and isovector pairing channels.

Automated summary

This study analyzes the contribution of isovector and isoscalar proton-neutron pairing to the binding energies of even-even nuclei with N - Z = 0, 2, 4 and atomic mass 20 < A < 100. The binding energies are calculated using a mean-field approach coupled with a Skyrme-type functional and a zero-range isovector-isoscalar pairing force. The pairing force is treated in the framework of the quartet condensation model (QCM) which preserves particle number and isospin exactly. The interdependence of pairing and deformation is taken into account through self-consistent Skyrme-HF + QCM calculations in the intrinsic system. It is shown that the binding energies do not change significantly when the isoscalar pairing is activated, which can be attributed to the less attractive off-diagonal matrix elements of the isoscalar force and the competition between isoscalar and isovector pairing channels.