S × S geometries in ABJM and giant gravitons

We construct a new NS5-brane solution in AdS4 × CP with S × S topology. This solution belongs to the general class of non-EinsteinN11 metrics to which T 1,1 belongs, and carries a non-vanishing D0-brane charge. In eleven dimensions it gives rise to a squashed S× S M5-brane giant graviton which is now of the N10 type. The energies of both solutions satisfy the BPS bound E = kQ/2, indicating supersymmetric configurations, where Q is interpreted as D0-brane charge for the NS5-brane and as angular momentum for the dynamically stable M5-brane giant graviton. The ground state is degenerate with a spherical D2 or M2-brane, rather than with a point-like object. Moreover, while the charge of the spherical 2-brane can be arbitrary, the charge of the S×S 5-brane is bounded by N/2, with N the rank of the ABJM gauge group, a manifestation of the stringy exclusion principle. A microscopic description, suitable for the study of the finite ’t Hooft coupling region, is provided in terms of spherical D2 or M2-branes expanding into fuzzy 3-spheres.