  We consider the equilibrium behavior of fluids imbibed in disordered
mesoporous media, including their gas-liquid critical point when present. Our
starting points are on the one hand a description of the fluid/solid-matrix
system as a quenched-annealed mixture and on the other hand the Hierarchical
Reference Theory (HRT) developed by A. Parola and L. Reatto to cope with
density fluctuations on all length scales. The formalism combines liquid-state
statistical mechanics and the theory of systems in the presence of quenched
disorder. A straightforward implementation of the HRT to the quenched-annealed
mixture is shown to lead to unsatisfactory results, while indicating that the
critical behavior of the system is in the same universality class as that of
the random-field Ising model. After a detour via the field-theoretical
renormalization group approach of the latter model, we finally lay out the
foundations for a proper HRT of fluids in a disordered porous material.
