Neutron-Proton pairing revisited

Abstract

We reexamine neutron-proton pairing as a phenomenon that should be explanable in a microscopic theory of nuclear binding energies. Empirically, there is an increased separation energy when both neutron and proton numbers are even or if they are both odd. The enhancement is present at some level in nearly all nuclei: the separation energy difference has the opposite sign in less than 1% of the cases in which sufficient data exist. We discuss the possible origin of the effect in the context of density functional theory (DFT) and its extensions. Neutron-proton pairing from the Hartree-Fock-Bogoliubov theory does not seem promising to explain the effect. We demonstrate that much of the increased binding in the odd-odd system might be understood as a recoupling energy. This suggests that the DFT should be extended by angular momentum projection to describe the effect.

9 pages, 5 figures, 1 table

References in corpus (8)

• Local Density Approximation for proton-neutron pairing correlations. I. Formalism
• Global study of quadrupole correlation effects
• Competition Between T=0 and T=1 Pairing in Proton-Rich Nuclei
• The Origin of the Wigner Energy
• Neutron-proton pairing in the BCS approach
• Microscopic structure of fundamental excitations in N=Z nuclei
• Rotations in isospace: a doorway to the understanding of neutron-proton superfluidity in N=Z nuclei
• Global study of the spectroscopic properties of the first 2+ state in even-even nuclei

Cited by in corpus (10)

• Odd-even mass differences from self-consistent mean-field theory
• Superfluidity in nuclear systems and neutron stars
• Experimental effects on dynamics and thermodynamics in nuclear reactions on the symmetry energy as seen by the CHIMERA 4$\pi$ detector
• Skyrme-Hartree-Fock-Bogoliubov mass models on a 3D mesh: II. Time-reversal symmetry breaking
• $N=Z$ nuclei: A laboratory for neutron-proton collective mode
• Empirical residual neutron-proton interaction in odd-odd nuclei
• Global phenomenological descriptions of nuclear odd-even mass staggering
• Influence of secondary decay on odd-even staggering of fragment cross sections
• Whence the odd-even staggering in nuclear binding?
• Extrapolations of nuclear binding energies from new linear mass relations