We generalize a recent model-independent form factor parametrization derived from rigorous dispersion relations to include constraints from data in the timelike region. These constraints dictate the convergence properties of the parametrization and appear as sum rules on the parameters. We further develop a new parametrization that takes into account finiteness and asymptotic conditions on the form factor, and use it to tit to the elastic π electromagnetic form factor. We find that the existing world sample of timelike data gives only loose bounds on the form factor in the spacelike region, but we explain how the acquisition of additional timelike data and fits to other form factors are expected to give much better results. The same parametrization is seen to fit spacelike data extremely well.
|Original language||English (US)|
|Journal||Physical Review D - Particles, Fields, Gravitation and Cosmology|
|State||Published - Sep 1 1998|
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)