Space-time Vector Supersymmetry and Massive Spinning Particle
  We construct the action of a relativistic spinning particle from a non-linear realization of a space-time odd vector extension of the Poincar\'e group. For particular values of the parameters appearing in the lagrangian the model has a gauge world-line supersymmetry.{As a consequence of this local symmetry there are BPS solutions in the model preserving 1/5 of the supersymmetries.} A supersymmetric invariant quantization produces two decoupled 4d Dirac equations. 
Roberto Casalbuoni (Department of Physics, University of Florence,   INFN-Florence and Galileo Galilei Institute, Florence, ...