Pointlike constituent quarks and scattering equivalences
  In this paper scattering equivalences are used to simplify current operators in constituent quark models. The simplicity of the method is illustrated by applying it to a relativistic constituent quark model that fits the meson mass spectrum. This model requires a non-trivial constituent quark current operator to fit the pion form factor data. A model with a different confining interaction, that has the identical spectrum and can reproduce the measured pion form factor using only point-like constituent quark impulse currents is constructed. Both the original and transformed models are relativistic direct-interaction models with a light-front kinematic subgroup. 
Evan Sengbusch, W. N. Polyzou