Massive Relativistic Particle Model with Spin and Electric Charge from   Two-Twistor Dynamics
  The sixteen real coordinates of two-twistor space are transformed by a nonlinear mapping into an enlarged space-time framework. The standard relativistic phase space of coordinates $(X_\mu, P_\mu)$ is supplemented by a six-parameter spin phase manifold (two pairs $(\eta_\alpha,\sigma_\alpha)$ and $(\bar{\eta}_{\dot\alpha}, \bar{\sigma}_{\dot{\alpha}})$ of canonically conjugated Weyl spinors constrained by two second class constraints) and the electric charge phase space ($e,\phi$). The free two-twistor classical mechanics is rewritten in this enlarged relativistic phase space as a model for a relativistic particle. Definite values for the mass, spin and the electric charge of the particle are introduced by means of three first class constraints. 
A.Bette (Royal Inst.Techn., Sodertalje), A. de Azcarraga   (Dept.Fis.Teor. and IFIC, Univ. Valencia), J.Lukierski (Inst.Theo...