About Mass, CP and Extra Dimensions
  We discuss the notion of mass, mostly for fermions, and its relation to the breaking of CP invariance, the natural symmetry of gauge interactions. In a first model, we show how compactification on a Vortex in 2 extra dimensions leads to a replication of generations in 3+1, with challenging mass patterns, and testable consequences in flavour-changing neutral currents (family-number conserving), both at low energies and at future colliders. In different model, we show how CP violation can result from compactification from 4+1 to 3+1 dimensions. 
J.-M. Fr\`ere