Continuous-spin particle field theory with helicity correspondence

We propose the first covariant local action describing the propagation of a single free continuous-spin degree of freedom. The theory is simply formulated as a gauge theory in a “vector superspace,” but can also be formulated in terms of a tower of symmetric tensor gauge fields. When the spin invariant $\rho$ vanishes, the helicity correspondence is manifest—familiar gauge theory actions are recovered and couplings to conserved currents can easily be introduced. For nonzero $\rho$, a tower of tensor currents must be present, of which only the lowest rank is exactly conserved. A paucity of local gauge-invariant operators for nonzero $\rho$ suggests that the equations of motion in any interacting theory should be covariant, not invariant, under a generalization of the free theory’s gauge symmetry.