Perturbative and Non-perturbative N =8 Supergravity

Understand

We study extremal black holes, their ADM mass and area of the horizon in N = 8 supergravity.

• Contrary to intuition gained from N = 2, 4 theories, in N = 8 supergravity BPS states may become massless only at the boundary of moduli space.
• We show that stringy states described in [1], which have no mass gap and survive in the toroidal compactification in addition to massless states of perturbative N = 8 supergravity, display a null singularity in four-dimensional space-time, when viewed as solutions of N = 8 Einstein equations.
• We analyze known methods of resolving such singularities and explain why they do not work in D=4, N = 8 supergravity.