Instantons and the chiral phase transition at nonzero baryon density

We study an interacting ensemble of instantons at a finite baryon chemical potential. We emphasize the importance of fermionic zero modes and calculate the fermion induced interaction between instantons at a nonzero chemical potential. We show that unquenched simulations of the instanton ensemble are feasible in two regimes, for a sufficiently small and for a very large chemical potential. At a very large chemical potential chiral symmetry is restored and the instanton ensemble is dominated by strongly correlated chainlike configurations. [S0556-2821(98)03407-9].