ELECTROMAGNETIC FORM FACTORS OF THE NUCLEON IN SPACELIKE AND TIMELIKE REGIONS

An approach for a unified description of the nucleon electromagnetic form factors in spacelike and timelike regions is presented. The main ingredients of our model are: i) a Mandelstam formula for the matrix elements of the nucleon electromagnetic current; ii) a 3-dimensional reduction of the problem on the Light-Front performed within the so-called Propagator Pole Approximation (PPA), which consists in disregarding the analytical structure of the Bethe-Salpeter amplitudes and of the quark-photon vertex function in the integration over the minus components of the quark momenta; iii) a dressed photon vertex in the channel, where the photon is described by its spin-1, hadronic component.