s-wave halo effect and the Coulomb barrier top effect on the mirror state of a halo

The Thomas-Ehrman shift for ¹¹Be and ¹¹N mirror nuclei, which was recently observed as a differential energy shift between s and other orbital states, is investigated in terms of complex expectation values. In calculating the complex expectation values, we use a new method which was recently proposed within the framework of the complex scaling method. The physical origin of the energy shift can be understood by considering the effects of the s-wave halo and the Coulomb barrier top. These two effects are discussed as another proof of a halo in addition to the observation of large matter radii in the drip-line nuclei.