Pauli blocking effects in low-energy πd scattering?

Pauli blocking effects in low-energy pi d scattering, as recently discussed in this journal, are spurious, because multiple-scattering expansions based on the Watson-Faddeev method of employing two-body t-matrices do allow and require intermediate baryonic states that violate the Pauli principle. It is found that substantial cancellations occur in the double-scattering term between contributions from even-L and odd-L intermediate NN states; only by retaining all of these contributions is the stability observed by other authors in the evaluation of the pi d scattering length recovered.