New constraints on dispersive form factor parametrizations from the timelike region

W. W. Buck, Richard F. Lebed

Research output: Contribution to journalArticle


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 languageEnglish (US)
Article number056001
Pages (from-to)560011+5600112
JournalPhysical Review D - Particles, Fields, Gravitation and Cosmology
Issue number5
StatePublished - Sep 1 1998
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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