The electro - magnetic Form Factors of the Proton in chiral Soliton Models ∗ Gottfried

The electro-magnetic form factors of the proton are calculated in a chiral soliton model with relativistic corrections. The magnetic form factor GM is shown to agree well with the new SLAC data for spacelike Q2 up to 30 (GeV/c)2 if superconvergence is imposed. The direct continuation through a Laurent series to the timelike region above the physical threshold is in fair agreement with the presently available set of data. The electric form factor GE is dominated by a zero in the few (GeV/c) 2 region which appears to be in conflict with the SLAC data. Contribution to the Sixth International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon, Blaubeuren/Tuebingen, Germany, 10-14 July, 1995 e-mail address : [email protected] 1 Relativistic soliton form factors The new SLAC data for electro-magnetic form factors (FF) of the proton to high Q pose a challenging test for the relativistically corrected FFs of chiral soliton models. It has repeatedly been demonstrated for various versions of chiral lagrangians that the nucleon e.m. FFs are rather well accounted for low Q with nucleons as nonrelativistic solitons in coupled π, ̺, and ω fields. The implementation of relativistic corrections is especially easy for solitonic nucleons due to the Lorentz covariance of the field equations (in contrast to the corresponding problem in bag models). The corrections reflect the Lorentz boost from the soliton rest frame to the Breit frame, in which the soliton moves with velocity v which satisfies γ = (1− v) = 1 + Q 2 (2M)2 (1) for momentum transfer Q (Q > 0 in the spacelike region) and soliton massM . The classical result for the magnetic FF is GM(Q ) = 1 1 + Q 2 (2M) G M 