  The Inonu-Wigner contraction is applied to special relativity and the little
groups of the Lorentz group. If the O(3) symmetry group for massive particle is
boosted to an infinite-momentum frame, it becomes contracted to a combination
of the cylindrical group and the two-dimensional Euclidean group. The Euclidean
component becomes the Lorentz condition applicable to the electromagnetic
four-potential, and the cylindrical component leads to the helicity and gauge
degrees of freedom. The rotation around the cylindrical axis corresponds to the
helicity, while the translation parallel to the axis on the cylindrical surface
leads to a gauge transformation.
