Abstract:  We show that the equations of motion for (free) integer higher spin gauge fields can be formulated as twisted selfduality conditions on the higher spin curvatures of the spins field and its dual. We focus on the case of four spacetime dimensions, but formulate our results in a manner applicable to higher spacetime dimensions. The twisted selfduality conditions are redundant and we exhibit a nonredundant subset of conditions, which have the remarkable property to involve only firstorder derivatives with respect to time. This nonredundant subset equates the electric field of the spins field (which we define) to the magnetic field of its dual (which we also define), and vice versa. The nonredundant subset of twisted selfduality conditions involve the purely spatial components of the spins field and its dual, and also the components of the fields with one zero index. One can get rid of these gauge components by taking the curl of the equations, which does not change the
ir physical content. In this form, the twisted selfduality conditions can be derived from a variational principle that involves prepotentials, which are the higher spin generalizations of the prepotentials previously found in the spins 2 and 3 cases. The prepotentials have again the intriguing feature of possessing both higher spin diffeomorphism invariance and higher spin conformal geometry. The tools introduced in an earlier paper for handling higher spin conformal geometry turn out to be crucial for streamlining the analysis. In four spacetime dimensions where the electric and magnetic fields are tensor fields of the same type, the twisted selfduality conditions enjoy an SO(2) electricmagnetic invariance. We explicitly show that this symmetry is an "offshell symmetry" (i.e., a symmetry of the action and not just of the equations of motion). Remarks on the extension to higher dimensions are given.
