Dynamical Calculation of Extinct Bound States

Aspects of the possible dynamical extinction of a bound state (coincident zero in $N$ and $D$) are discussed within the single and multichannel $N{D}^{-1\mathrm{}}$ framework. A surprising result is that, within any one-channel calculation, the "mass" of the extinct bound state cannot be calculated. This may be reflected in the multichannel formulation by a particular sensitivity of the "mass" to the input.