Flux Compactification of M-theory on Compact Manifolds with Spin(7)   Holonomy
  At the leading order, M-theory admits minimal supersymmetric compactifications if the internal manifold has exceptional holonomy. The inclusion of non-vanishing fluxes in M-theory and string theory compactifications induce a superpotential in the lower dimensional theory, which depends on the fluxes. In this work, we verify the conjectured form of this superpotential in the case of warped M-theory compactifications on Spin(7) holonomy manifolds. We calculate the most general causal N=1 three-dimensional, gauge invariant action coupled to matter in superspace and derive its component form using Ectoplasmic integration theory. We also derive a perturbative set of solutions which emerges from a warped compactification on a Spin(7) holonomy manifold with non-vanishing flux for the M-theory field strength and we show that in general the Ricci flatness of the internal manifold is lost. Using the superpotential form we identify the supersymmetric vacua out of this general set of solutions. 
Dragos Constantin