Physical wave functions for the nucleon and the $\Delta^{ +}$ isobar are presented, which unify the best features of previous models. With these wave functions we can calculate elastic form factors and the decays of the charmonium levels ${ }^{ 3}S_{ 1}$, ${ }^{ 3}P_{ 1}$, ${ }^{ 3}P_{ 2}$ into $p\bar p$ in agreement with the data. A striking scaling behavior between $R=|G_{ \text{ M}}^{ \text{ n}}|/G_{ \text{ M}}^{ \text{ p}}$ and the coefficient $B_{ 4}$ of the Appell polynomial decomposition of the nucleon distribution amplitude is found; the implications for elastic nucleon cross sections are discussed.
Categories: hep-ph