Nucleon and γN → Δ lattice form factors in a constituent quark model

A covariant quark model, based both on the spectator formalism and on vector meson dominance, and previously calibrated by the physical data, is here extended to the unphysical region of the lattice data by means of one single extra adjustable parameter-the constituent quark mass in the chiral limit. We calculated the nucleon (N) and the gamma N -> Delta form factors in the universe of values for that parameter described by quenched lattice QCD. A qualitative description of the nucleon and gamma N -> Delta form factors lattice data is achieved for light pions.