  Self-assembly is the mechanism that controls the formation of well defined
structures from disordered pre-existing parts. Despite the importance of
self-assembly as a manufacturing method and the increasingly large number of
experimental realizations of complex self-assembled nano aggregates,
theoretical predictions are lagging behind. Here we show that for a non-trivial
self-assembly phenomenon, originating branched loop-less clusters, it is
possible to derive a fully predictive parameter-free theory of equilibrium
self-assembly by combining the Wertheim theory for associating liquids with the
Flory-Stockmayer approach for chemical gelation.
