S^2 x S^3 geometries in ABJM and giant gravitons

Abstract: We construct a new NS5-brane solution in AdS_4 x CP^3 with S^2 x S^3 topology. This solution belongs to the general class of non-Einstein N_{11} 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^2 x S^3 M5-brane giant graviton which is now of the N_{10} 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^2 x S^3 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.