11D Supergravity and Hidden Symmetries

We review the structure of maximal D = 11 and D = 10 supergravities. Upon dimensional reduction, these theories give rise to the unique maximal supergravities in all lower spacetime dimensions D < 10. In D dimensions, maximal supergravity exhibits the exceptional global symmetry group E11−D, part of which is realized as hidden symmetries and only manifest after proper dualization of the fields. We also briefly review the reformulation of D = 11 supergravity as an exceptional field theory, which renders the appearance of hidden symmetries manifest.