Symmetry restoration in the mean-field description of proton-neutron pairing

Abstract

We show that the symmetry-restored paired mean-field states (quasiparticle vacua) properly account for isoscalar versus isovector nuclear pairing properties. Full particle-number, spin, and isospin symmetries are restored in a simple SO(8) proton-neutron pairing model, and prospects to implement a similar approach in a realistic setting are delineated. Our results show that, provided all symmetries are restored, the pictures based on pair-condensate and quartet-condensate wave functions represent equivalent ways of looking at the physics of nuclear proton-neutron pairing. Keywords: Mean field, Proton-neutron pairing, Isoscalar pairing, Symmetry restoration, Pair-transfer amplitudes, SO(8) pairing model