Two- and three-body structure of the Y(4660)

We study general features of three-meson bound states using the Y(4660) as an example. Here the Y(4660) is assumed to be either a two-body bound state of the f0(980), itself a bound state of K and K¯, and the ψ′=ψ(2s), or a three-body bound state of ψ′, K, and K¯. In particular, we investigate in detail the interplay of the various scales inherent in the problem, namely the f0 binding energy, the Y binding energy, and the Kψ′ scattering length. This allows us to understand under which circumstances the substructure of the f0(980) can be neglected in the description of the Y(4660).