STABILITY ANALYSIS OF SUM-RULES FOR PION COMPTON-SCATTERING

We perform a stability analysis of a recently proposed sum rule for pi on Compton scattering at fixed angle and moderate Mandelstam invariant s. The sum rule is found to be sensitive to the parameter lambda2, the contour radius of a generalized Borel transform. A modified phenomeno logical model for the continuum contribution is proposed to remove thi s dependence. It is shown that the best value of the quark-hadron dual ity interval s0 = 0.6 GeV2 is close to that in the form factor case (s 0 = 0.7 GeV2). The application of this new model to the pion form fact or is examined. A comparison of our predictions with those derived fro m a modified perturbative calculation including Sudakov suppression is also briefly considered.