When is it possible to use perturbation technique in field theory ?
Abstract
Description
The vector pion form factor is used as an example to analyze this question. Given the experimental radius of the pion, the crucial question is whether perturbative methods could be used for the effective chiral lagrangian to calculate the pion form factor. Our analysis shows that the pion rms radius is far too large (or the related rho resonance mass is too low) for the perturbation theory to be valid.
11 pages, Latex, 4 eps figs. Contribution to the proceedings of the workshop "QCD2000" Villefranche-sur-Mer, France, January 2000
11 pages, Latex, 4 eps figs. Contribution to the proceedings of the workshop "QCD2000" Villefranche-sur-Mer, France, January 2000