Relative amplitude in the mixed-spin pn superfluid phase

Abstract

Similar to short-range correlated electron pairs under the constraint of long-range Coulomb interaction, which describe condensed atomic states, isoscalar (T=0) and isovector (T=1) pn correlations, including short-range pairing and long-range non-pairing components, are respectively exclusive for nuclei in the vicinity of the N=Z line. In the framework of spherical shell model, these are found to be connected by two angle dependent control parameters cos2⁡θT=0cos2⁡θT=1 and sin2⁡θT=0sin2⁡θT=1 of U(1) gauge symmetry breaking in the T=1→0 quantum phase transition. The former, which serves as the relative amplitude, reveals a complex mixing between spin singlet (S=0) or T=1 and triplet (S=1) or T=0 pn pairing phases. The long-standing elusiveness of T=0 pairing phase is here explained by not only the quenching of T=0 pairing correlation but also the less prominent pairing element among strong T=0 interactions on average, while the appearance of T=1 pn pairing phase is naturally related to the enhancement and prominence of T=1 pairing interaction.

Keywords

• Shell model
• Isoscalar and isovector
• Proton-neutron pairing
• Mixed-spin
• Superfluid phase