Cranking in isospace - towards a consistent mean-field description of N=Z nuclei

Abstract

Excitation spectra of T=0,1,2 states in even-even (e-e) and odd-odd (o-o) N=Z nuclei are analyzed within a mean-field based model involving isovector and isoscalar pairing interactions and the iso-cranking formalism applied to restore approximately isospin symmetry. It is shown that T=0 states in o-o and T=1 states in e-e nuclei correspond to two-quasiparticle, time-reversal symmetry breaking excitations since their angular momenta are different than zero. On the other hand the lowest T=2 states in e-e and T=1 states in o-o nuclei, which both are similar in structure to their even-even isobaric analogue states, are described as e-e type vaccua excited (iso-cranked) in isospace. It appears that in all cases isoscalar pairing plays a crucial role in restoring the proper value of the inertia parameter in isospace.