Bagger-Lambert theory on an orbifold and its relation to Chern-Simons-matter theories

We consider how to take an orbifold reduction for the multiple M2-brane theory recently proposed by Bagger and Lambert, and discuss its relation to Chern-Simons theories. Starting from the infinite dimensional 3-algebra realized as the Nambu bracket on a 3-torus, we first suggest an orbifolding prescription for various fields. Then we introduce a second truncation, which effectively reduces the internal space to a 2-torus. Eventually one obtains a large-N limit of Chern-Simons gauge theories coupled to matter fields. We consider an abelian orbifold C^4/Z_n, and illustrate how one can arrive at the N=6 supersymmetric theories with gauge groups U(N) x U(N) and Chern-Simons levels (k,-k), as recently constructed by Aharony, Bergman, Jafferis and Maldacena.
20 pages; v3. major revision, title and abstract changed. to appear in Phys.Rev.D