Classical spin variables and classical counterpart of the Dirac-Feynman-Gell-Mann equation

In an extended relativistic fluid droplet, it is possible to define new internal variables which correspond to the classical counterpart of spin. If we introduce a new constraint, different from Weysenhoff's, we obtain by quantisation the Feynman-Gell-Mann wave equation. This also yields a theoretical connection between mass and spin which can be compared with the observed baryon boson mass spectrum.