Analytic model represents well both time-like and space-like emNN recations
Earle Lomon
MIT
A model of vector-meson dominance with asDymptotic pQCD has been shown to reproduce and predict the space-like electromegnetic form factors of the proton and neutron. As the form of the model is analytic, it is natural to ask whether it can simultaneously reproduce the time-like reaction electron-positron -> nucleon-antinucleon (and its inverse). As the form fitting the dispersion relation calculations for the effect of the rho meson width in the space-like region was phenomenological and unsuitable for the time-like region, the first step was to replace it with Breit- Wigner distributions and apply them to all vector mesons with substantial width. We will discuss the possible relativistic BW forms. We will display the reasonable fits obtained in the limit of vanishing mass for the mesons into which the vector mesons decay, and discuss the continuing work with the masses of those decay mesons included.