Threre is the famous proposal that -- in analogy to the role of generalized (doubled) geometry in type II string theory -- there should be exceptional generalized geometry for M-theory, with generalized tangent bundle not of the form \(T \oplus T^\ast\) (for momenta and string charges) but of the form

\(T \oplus \wedge^2 T^\ast \oplus \wedge^5 T^\ast \oplus \cdots\)

(for momenta and M2-brane charges and M5-brane charges) on which U-duality groups such as at least \(E_{k \leq 7}\) are naturally represented.

This proposal is due to

and it has excellent motivation and plausibility checks, even though a comprehensive development of exceptional generalized geometry (EGG) as a theory is still in the making.

What I am wondering is, and that's my question here, if anyone had ever noticed (in print or in some citable form) that there exists a more systematic mathematical derivation of this structure of the M-theory generalized tangent bundle which predates the EGG proposal by a margin, but was maybe not put in proper connection with it yet.

Namely the main result (last section) of

of which a more comprehensive analysis later appeared in

is the identification of a super Lie algebra extension of 11d super Minkowski spacetime on which the M2-brane 4-cocycle (the one that makes the brane scan).trivializes. (That's not quite how these authors phrase it, but this is exactly what they do, when phrased super Lie-theoretically.) And the bosonic body of that extension turns out to be none other than...

\(\mathbb{R}^{10,1} \oplus \wedge^2 (\mathbb{R}^{10,1})^\ast \oplus \wedge^5 (\mathbb{R}^{10,1})^\ast\)

hence none other than the fiber space of the exceptional tangent bundle.

It is natural to wonder about what this *means. *I am aware of speculations that this extended spacetime super Lie algebra itself is a contraction limit of the orthosymplectic \(\mathfrak{osp}(1|32)\) or the like, for instance in

* J.J. Fernandez, J.M. Izquierdo, M.A. del Olmo, *Contractions from osp(1|32)⊕osp(1|32) to the M-theory superalgebra extended by additional fermionic generators (*arXiv:1504.05946)

but what I have not see yet is anyone making the relation between this "hidden supergroup" of 11-dimensional supegravity and the generalized tangent bundle of exceptional generalized geometry.

Mainly I am just asking for a citable reference, if any, that might make the relation. But of course if you have any other insights to share, I'd be interested,too.