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Electromagnetic form factors of the nucleon in the space-like region areinvestigated within the framework of a covariant and confiningNambu-Jona-Lasinio model. The bound state amplitude of the nucleon is obtainedas the solution of a relativistic Faddeev equation, where diquark correlationsappear naturally as a consequence of the strong coupling in the colour$\bar{3}$ $qq$ channel. Pion degrees of freedom are included as a perturbationto the "quark-core" contribution obtained using the Poincar\'e covariantFaddeev amplitude. While no model parameters are fit to form factor data,excellent agreement is obtained with the empirical nucleon form factors(including the magnetic moments and radii) where pion loop corrections play acritical role for $Q^2 \lesssim 1\,$GeV$^2$. Using charge symmetry, the nucleonform factors can be expressed as proton quark sector form factors. The latterare studied in detail, leading, for example, to the conclusion that the$d$-quark sector of the Dirac form factor is much softer than the $u$-quarksector, a consequence of the dominance of scalar diquark correlations in theproton wave function. On the other hand, for the proton quark sector Pauli formfactors we find that the effect of the pion cloud and axialvector diquarkcorrelations overcomes the effect of scalar diquark dominance, leading to alarger $d$-quark anomalous magnetic moment and a form factor in the $u$-quarksector that is slightly softer than in the $d$-quark sector.

Role of diquark correlations and the pion cloud in nucleon elastic form factors