E 8 in N= 8 supergravity in four dimensions

Abstract

We argue that N= 8 supergravity in four dimensions exhibits an exceptional E8(8) symmetry, enhanced from the known E7(7) invariance. Our procedure to demonstrate this involves dimensional reduction of the N= 8 theory to d = 3, a field redefinition to render the E8(8) invariance manifest, followed by dimensional oxidation back to d = 4.