Wrapped M-Branes in Their Gravity Duals

We investigate a class of N = 4 quiver Chern-Simons theories and their gravity duals. We define the group of fractional D3-brane charges in a type IIB brane setup taking account of D3-brane creation due to the Hanany-Witten effect, and confirm that it agrees with the 3-cycle homology of the dual geometry, which describes the charges of fractional M2-branes, i.e., M5-branes wrapped on 3-cycles. The relation between the fractional brane charge and the torsion of the 3-form potential field is partially established. We also discuss the duality between baryonic operators in the Chern-Simons theories and M5-branes wrapped on 5cycles in the dual geometries. The degeneracy and the conformal dimension of the operators are reproduced on the gravity side. We also comment on the relation between wrapped M2branes and monopole operators. The baryonic operators we consider are not gauge-invariant. We argue that gauge invariance cannot be imposed on all the operators corresponding to wrapped M-branes in the AdS4/CFT3 correspondence.