Generalized Symmetries of Massless Free Fields on Minkowski Space

Abstract

A complete and explicit classification of generalized, or local, symmetries of massless free fields of spin s 1/2 is carried out. Up to equivalence, these are found to consists of the conformal symmetries and their duals, new chiral symmetries of order 2s, and their higher-order extensions obtained by Lie differentiation with respect to confor- mal Killing vectors. In particular, the results yield a complete classification of generalized symmetries of the Dirac-Weyl neutrino equation, Maxwell's equations, and the linearized gravity equations.