We consider supersymmetry in five dimensions, where the fermionic parameters are a 2-form under SL(5). Supermultiplets are investigated using the pure spinor superfield formalism, and are found to be closely related to infinite-dimensional extensions of the supersymmetry algebra: the Borcherds superalgebra ℬ(E 4 ), the tensor hierarchy algebra S(E 4 ) and the exceptional superalgebra E(5, 10). A theorem relating ℬ(E 4 ) and E(5, 10) to all levels is given.
Introduction and OverviewSupersymmetry provides an extension of bosonic space-time symmetries with fermionic generators. These are generically spinors under space-time rotations (and may also transform under R-symmetry). In certain situations, supersymmetry generators in non-spinorial modules may be considered. The main example is provided by "twisting", where one considers a fermionic generator which is a singlet under some subalgebra.More generically, one may a priori consider an assignment where supersymmetry generators come in a module S of a spacetime "structure group" G, which we think of as corresponding to the double cover of the Lorentz group together with R-symmetry. A supersymmetry algebra will take the form 1 [Q a , Q b ] = c ab m P m , with some invariant tensor c, and the rest of the brackets vanishing. The only condition is that the symmetric product ∨ 2 S contains the vector representation V.Presently, we will consider one specific such assignment, namely when the structure group is G = SL(5), V = 5 and S = 10. The supersymmetry algebra then is 2 [Q mn , Q pq ] = 2𝜖 mnpqr 𝜕 r ,(1.1