J. Argyris et al., INFINITESIMAL LORENTZ TRANSFORMATIONS AND THE STATES OF POLARIZATION OF FREE PHOTONS, Foundations of physics letters, 11(3), 1998, pp. 277-285
Applying the tangent dynamics technique as generated by infinitesimal
Lorentz transformations, it is shown that the components of an electro
magnetic field correspond to the Lie-Cartan parameters of the group SO
(3,1). Thus the maximum number of non-null components of the magnetic
field (i.e., the number of the states of polarization) is not decided
by the number of group generators.