Coisotropic D-branes on AdS4 x CP3 and massive deformations

We scan for massive type IIA SU(3)-structure compactifications of the type AdS4 x CP3 with internal symmetry group SO(4). This group acts on CP3 with cohomogeneity one, so that one would expect new non-homogeneous solutions. We find however that all such solutions enhance their symmetry group to Sp(2) and form, in fact, the homogeneous family first described in [1]. This is in accordance with [2], which argues from the CFT-side that although new vacua with SO(4) symmetry group and N = 2 supersymmetry should exist, they fall outside our ansatz of strict SU(3)-structure, and instead have genuine SU(3) x SU(3)-structure. We do find that the SO(4)-invariant description, which singles out one preferential direction in the internal space, is well-adapted for describing the embedding of AdS4-filling supersymmetric D8-branes on both the original ABJM configuration and its massive Sp(2)-symmetric deformations. Supersymmetry requires these D-branes to be of the coisotropic type, which means in particular that their world-volume gauge field must be non-trivial.