The first three coefficients of the Taylor's series expansion of the vevtor pion form factor as a function of the momentum transfer are evaluated using the experimental data on the pion form factor and the P-wave \(\pi\pi\) phase shifts. The real part of the form factor as a function of energy is also calculated by dispersion relation. Comparisons there results with Chiral Perturbation Theory and unitarized models are given.
The prediction that the use of the Borkowski form factor for proton in the Chou-Yang model for π−p elastic scattering at 200 GeV/c yields multiple dip structure in the region −5 ≲ −t ≲ 8 (GeV/c) 2 is shown to be incorrect. A parameterization of the proton form factor obtained by including the new experimental data for large −t when used in conjunction with pion form factor also does not produce the observed dip near −t = 4 (GeV/c) 2. Three possible approaches for a solution of the problem are briefly discussed.
Taylor's Series and Dispersion Relation Analyses of the Vector Pion Form Factor and their Comparison with Perturbative and Non Perturbative Calculations
