Scaling of the nucleon e.m. elastic form factors: A general derivation

The scaling of the elastic e.m. form factors of the nucleon (p charge form factor and magnetic form factors of p and n) has been discussed so far mainly in the non relativistic quark model. We ask: Can the scaling be derived in a model independent way from general properties of QCD? Using the QCD general parametrization we show that: (1) The magnetic form factors of p and n are expected to scale in QCD to a few percent; (2) As to the p electric and magnetic form factors, their scaling, in general, is not guaranteed. The most likely explanation of its empirical validity is that only the “valence quarks” determine the expectation values of both the local charge and magnetization density; the effects of “sea” quarks and antiquarks cancel locally, on the average, as far as the p form factors are concerned.