Dual Giant Gravitons in Sasaki-Einstein Backgrounds

We study the dynamics of BPS D3-branes wrapped on a three-sphere in AdS_5 x L, so-called dual giant gravitons, where L is a Sasakian five-manifold. The phase space of these configurations is the symplectic cone X over L, and geometric quantisation naturally produces a Hilbert space of L^2-normalisable holomorphic functions on X, whose states are dual to scalar chiral BPS operators in the dual superconformal field theory. We define classical and quantum partition functions and relate them to earlier mathematical constructions by the authors and S.-T. Yau, hep-th/0603021. In particular, a Sasaki-Einstein metric then minimises an entropy function associated with the D3-brane. Finally, we introduce a grand canonical partition function that counts multiple dual giant gravitons. This is related simply to the index-character of the above reference, and provides an elegant method for counting multi-trace scalar BPS operators in the dual superconformal field theory.