QED Coupling from a 5-D Kaluza-Klein Theory
  We discuss the possibility to obtain, from a five-dimensional free spinor Lagrangian, the Quantum Electro-Dynamics (QED) coupling via a Kaluza-Klein reduction of the theory. This result is achieved taking a phase dependence of the spinor field on the extra-coordinate and modifying the corresponding connection. The five-dimensional spinor theory is covariant under the admissible coordinates transformations and its four-dimensional reduction provides the QED coupling term. 
Andrea Marrocco and Giovanni Montani