COMPARING THE P-WAVE MULTIPOLES FOR PI(0) PHOTOPRODUCTION WITH LOW-ENERGY PREDICTIONS

Recent estimates of the p-wave multipoles for p(gamma, pi(0)) near threshold [J. C. Bergstrom, Phys. Rev. C 50, 2979 (1994)] are compared with new low-energy theorems (LETs) derived from heavy-baryon chiral perturbation theory. Very good agreement is obtained with the LET for the combination M(1+)-M(1-), but a marked discrepancy exists with the LET for E(1+). Comparison is also made with an explicit (model-dependent) evaluation of the multipoles which incorporates the off-shell behavior of the Delta(1232) resonance in a generalized covariant form. Excellent agreement is observed for the multipole M(1-) including the isospin components, but again a substantial discrepancy exists with E(1+). An experimental test of the conflicting E(1+) results is suggested.