By a realistic dynamical microscopic reaction approach to ${}_{}{}^5{}_{}{}^{}\mathrm{He}$ we reproduce the empirical positions of the two S matrix poles associated with the 3/$2^{+}$ resonance, and unambiguously prove that it arises from the t+d channel. The picture is not coherent though, unless the presently adopted α+n phase shift, extracted partly from α+p scattering data, is assumed to be incorrect. It is pointed out that the analog resonance in ${}_{}{}^5{}_{}{}^{}\mathrm{Li}$ behaves very differently because the shadow pole is located on another Riemann sheet.

• Received 13 October 1992

DOI:https://doi.org/10.1103/PhysRevLett.70.1389