Brane Resolution and Gravitational Chern-Simons terms
  We show that gravitational Chern-Simons corrections, associated with the sigma-model anomaly on the M5-brane world-volume, can resolve the singularity of the M2-brane solution with Ricci-flat, special holonomy transverse space. We explicitly find smooth solutions in the cases when the transverse space is a manifold of Spin(7) holonomy and SU(4) holonomy. We comment on the consequences of these results for the holographically related three-dimensional theories living on the world volume of a stack of such resolved M2-branes. 
Francisco A. Brito, Mirjam Cvetic, and Asad Naqvi