cost of considering only weak polydispersity. Although a final seattlement on the soundness of the latter method would require numerical simulations for the polydisperse Baxter model, we argue that this approach is expected to keep correctly into account the effects of polydispersity, at least qualitatively.'
author:
- |
    Domenico Gazzillo, Riccardo Fantoni & Achille Giacometti [^1]$^\ast$\
    Istituto Nazionale per la Fisica della Materia and Dipartimento di Chimica Fisica, Università di Venezia, S. Marta DD 2137, I-30123 Venezia, Italy
title: |
    Phase behavior of polydisperse sticky hard spheres:\
    analytical solutions and perturbation theory
---

Introduction
============

New technological advances in physico-chemical manipulation of colloidal mixtures have brought up again the issue of theoretically understanding the phase behaviour of polydisperse systems [@Sollich02]. ‘Polydispersity’ in colloidal solutions means that, due to their production process, suspended macroparticles with the same chemical composition cannot be exactly identical to each other, but in general have different sizes, and possibly different surface charges, shapes, etc. In practice, a polydisperse system can be reckoned as a mixture with very large – or essentially infinite – number $M$ of different species or components, identified by one or several parameters ($M$ large but finite refers to *discrete polydispersity*, whereas $M\rightarrow 