On the dispersion theory of $\pi \pi$ scattering

Abstract

Recent developments in low energy pion physics are reviewed, emphasizing the strength of dispersion theory in this context. As an illustration of the method, I discuss some consequences of the forward dispersion relation obeyed by the isoscalar component of the scattering amplitude.

Comments: Contribution to the proceedings of the workshop "Quark Confinement and the Hadron Spectrum VII", Ponta Delgada, Azores Islands, Portugal, September 2006