Mass mixing, the fourth generation, and the kinematic Higgs mechanism

We describe how to construct explicit chiral fermion mass terms using Dirac-Kähler (DK) spinors. Classical massive DK spinors are shown to be equivalent to four generations of Dirac spinors with equal mass coupled to a background U(2,2) gauge field. Quantization breaks U(2,2) to U(2)×U(2), lifts mass spectrum degeneracy, and generates a non-trivial CKM mixing.