A supersymmetric extension for AdS4 background was found by Konstein and Vasiliev in Nucl.Phys.B331:475-499,1990, and later generalised by Vasiliev in hep-th/0404124 to higher dimensions. In 4d, there are three classes of infinite-dimensional extended higher spin superalgebras which generate symmetries of the higher spin equations of motion on AdS4. In each case, the bosonic part contains a subalgebra of the form so(3,2)⊕g(m)⊕g(n), comprising the AdS4 isometries and g being either u, o or usp. The corresponding higher spin superalgebras are denoted hg(m,n|4). They contain the usual N-extended lie superalgebra osp(N|4) as a subalgebra only when m=n. Indeed, for m≠n, massless unitary irreps of hg(m,n|4) contain a different number of bosons and fermions. In the simplest class with g=u, bosons have all integer spins > 1 and are in the adjoint of u(m)⊕u(n) while fermions have all half-integer spins > 3/2 and are in the bifundamental of u(m)⊕u(n). (The standard spin 2 graviton is contained in a diagonal u(1) factor.) The amount of extended higher spin supersymmetry in this sense is therefore unconstrained.
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