G. Holzwarth, ELECTROMAGNETIC NUCLEON FORM-FACTORS AND THEIR SPECTRAL FUNCTIONS IN SOLITON MODELS, ZEITSCHRIFT FUR PHYSIK A-HADRONS AND NUCLEI, 356(3), 1996, pp. 339-350
It is demonstrated that in simple soliton models essential features of
the electro-magnetic nucleon form factors observed over three orders
of magnitude in momentum transfer t are naturally reproduced. The anal
ysis shows that three basic ingredients are required: an extended obje
ct, partial coupling to vector mesons, and relativistic recoil correct
ions. We use for the extended object the standard skyrmion, one vector
meson propagator for both isospin channels, and the relativistic boos
t to the Breit frame. Continuation to timelike t leads to quite stable
results for the spectral functions in the regime from the 2- or 3-pio
n threshold to about two rho masses, Especially the onset of the conti
nuous part of the spectral functions at threshold can be reliably dete
rmined and there are strong analogies to the results imposed on disper
sion theoretic approaches by the unitarity constraint.