Moduli spaces and brane solitons for M-theory compactifications on holonomy G(2) manifolds

We investigate the local geometry on the moduli space of G(2) Structures th at arises in compactifications of M-theory on holonomy G2 manifolds. In par ticular, we determine the homogeneity properties of couplings of the associ ated N = 1, D = 4 supergravity under the scaling of moduli space coordinate s. We then find some brane solitons of N = 1, D = 4 supergravity that are a ssociated with wrapping M-branes on cycles of the compact space. These incl ude cosmic strings and domain walls that preserve 1/2 of supersymmetry of t he four-dimensional theory, and nonsupersymmetric electrically and magnetic ally charged black holes. The geometry of some of the black holes is that o f nonextreme M-brane configurations reduced to four dimensions on a seven t orus. (C) 2001 Elsevier Science B.V. All rights reserved.