The meson-cloud model of the nucleon consisting of a system of three valence
quarks surrounded by a meson cloud is applied to study the electroweak
structure of the proton and neutron. Light-cone wavefunctions are derived for
the dressed nucleon as pictured to be part of the time a bare nucleon and part
of the time a baryon-meson system. Configurations are considered where the
baryon can be a nucleon or a \Delta and the meson can be a pion as well as a
vector meson such as the \rho or the \omega. An overall good description of the
electroweak form factors is obtained. The contribution of the meson cloud is
small and only significant at low Q^2. Mixed-symmetry S'-wave components in the
wavefunction are most important to reproduce the neutron electric form factor.
Charge and magnetization densities are deduced as a function of both the radial
distance from the nucleon center and the transverse distance with respect to
the direction of the three-momentum transfer. In the latter case a central
negative charge is found for the neutron. The up and down quark distributions
associated with the Fourier transform of the axial form factor have opposite
sign, with the consequence that the probability to find an up (down) quark with
positive helicity is maximal when it is (anti)aligned with the proton helicity.Comment: references updated and typos in figure 2 corrected; to be published
in Phys. Rev.