Halo or skin in the excited states of some light mirror nuclei

The properties of three pairs of mirror nuclei 13N- 13C, 15N- 15O and 21Na- 21Ne (these mirror nuclei are all made of a good inert core plus an unpaired valence nucleon) are investigated by using the nonlinear relativistic mean-field (RMF) theory. It is found that the calculated binding energies with two different parameter sets are very close to the experimental ones for both the ground states and the excited states except for the large deformed nuclei. The calculations show that the 2s 1/2 excited states of 15N and of 21Na are both weakly bound with a proton halo and a proton skin (or a pigmy proton skin), respectively. In addition, the 1d 5/2 excited state of 13C and the 2s 1/2 excited state of 15O are also weakly bound with a neutron skin, respectively. The ratio of the valence nucleon radius to matter radius is deduced and it can be regarded as an additional criterion for the existence of exotic structure. The unbound 2s 1/2 and 1d 5/2 excited states of 13N are also discussed