Applications of interior dispersion relations to pion photoproduction near threshold

Interior dispersion relations are applied in the boundary limit to the determination of certain threshold and subthreshold quantities for pion photoproduction, viz., the threshold s-wave multipole amplitudes E₀₊ⁱ, and the amplitudes involved in the current-algebra theorems of Fubini and Furlan, and of Adler and others. Where comparisons are possible, our results are consistent with determinations by other methods. We also find further substantiation for conclusions reached elsewhere concerning the continuation of soft-pion theorems to their on-shell versions.