Analytical solution of the radiative transfer equation for polarized light

A new formalism is introduced for the transfer of polarized radiation. Stokes parameters are shown to be four- vectors in a Minkowski-like space and, most strikingly, the ra- diative transfer equation (RTE) turns out to be an infinitesimal transformation under the Poincar´ e (plus dilatations) group. A solution to the transfer equation as a finite element of this group is proposed.