Higher spins from non-linear realizations of OSp(1|8)

We exhibit surprising relations between higher spin theory and non-linear realizations of the supergroup OSp(1|8), a minimal superconformal extension of N=1, 4D supersymmetry with tensorial charges. We construct a realization of OSp(1|8) on the coset supermanifold OSp(1|8)/SL(4,R) which involves the tensorial superspace R(10|4) and Goldstone superfields given on it. The covariant superfield equation encompassing the component ones for all integer and half-integer massless higher spins amounts to the vanishing of covariant spinor derivatives of the suitable Goldstone superfields, and, via Maurer-Cartan equations, to the vanishing of SL(4,R) supercurvature in odd directions of R(10|4). Aiming at higher spin extension of the Ogievetsky-Sokatchev formulation of N=1 supergravity, we generalize the notion of N=1 chirality and construct first examples of invariant superfield actions involving a non-trivial interaction. Some other potential implications of OSp(1|8) in the proposed setting are briefly outlined.