Stability Analysis of Sum Rules for Compton Scattering

Abstract

We perform a stability analysis of a recently proposed sum rule for pion Compton scattering at fixed angle and moderate Mandelstam invariants. The sum rule is found to be sensitive to the parameter ${\lambda }^2$, the contour radius of a generalized Borel transform. A modified phenomenological model for the continuum contribution is proposed to remove this dependence. It is shown that the best value of the quark-hadron duality interval $s_0=0.6$ GeV${}^2$ is close to that in the form factor case ($s_0=0.7$ GeV${}^2$). The application of this new model to the pion form factor is examined. A comparison of our predictions with those derived from a modified perturbative calculation including Sudakov suppression is also briefly considered.

Comments: 11 pages (latex), (CCUTH-93-1 preprint) 4 figs. availiable upon request (email:coriano@vana.physto.se)