Thomas-Ehrman effect in a three-body model: The Ne 16 case

The dynamic mechanism of the Thomas-Ehrman shift in three-cluster systems is studied by using the example of Ne-16 and C-16 isobaric mirror partners. We predict configuration mixings for 0(+) and 2(+) states in Ne-16 and C-16. Large isospin symmetry breaking on the level of wave function component weights is demonstrated for these states and discussed as a three-body mechanism of the Thomas-Ehrman shift. It is shown that the description of the Coulomb displacement energies requires consistency among three parameters: the Ne-16 decay energy ET, the F-15 ground-state energy E-r, and the configuration mixing parameters for the Ne-16 and (16)C0(+) and 2(+) states. Based on this analysis we infer the (15)F1/2(+) ground-state energy to be E-r = 1.39-1.42 MeV.