Comment on "Polarizability of the pion: No conflict between dispersion theory and chiral perturbation theory"

Abstract

The statement of the authors of the article Phys. Rev. C 77, 065211 (2008) that spurious singularities occur in the dispersion relation approach, where imaginary parts of the amplitudes of the process γγ->ππare saturated by the contributions of meson resonances by using Breit-Wigner expressions, is analyzed. It is shown that there are no any additional singularities in this approach and the disagreement between the predictions of the dispersion relations and the chiral perturbation theory for (α_1-β_1)_π^{\pm} remains.

3 pages, final version appeared in Phys. Rev. C