  We consider the 3-d Gross-Neveu model in the broken phase and construct a
stable brane world by means of a domain wall and an anti-wall. Fermions of
opposite chirality are localized on the walls and coupled through the 3-d bulk.
At large wall separation \beta the 2-d correlation length diverges
exponentially, hence a 2-d observer cannot distinguish this situation from a
2-d space-time. The 3-d 4-fermion coupling and \beta fix the effective 2-d
coupling such that the asymptotic freedom of the 2-d model arises. This
mechanism provides criticality without fine tuning.
