A consistent interacting massless higher-spin field theory in D = 2+1

An action is constructed in 2 + 1 spacetime dimensions describing interacting massless fields of all integer and half-integer spins s ≥ 3/2. The action is associated with an infinite-dimensional superalgebra, denoted shs(1,2) + shs (1,2). Truncation to the spin 3/2-spin 2 sector gives the (1,1) type anti-de Sitter supergravity theory corresponding to osp(1,2; R) + osp(1,2; R). Various properties of the D = 3 higher-spin theory, and its relevance to the higher-spin problem in four dimensions, are discussed. (author)