Quark condensate in the nuclear medium

The quark condensate in the nuclear medium taking into account the single-pion and two-pion exchanges between nucleons is calculated. The dependence of the condensate on the density of the matter ρ is found. At very low density the nonlinear terms are proportional to ρ2 and increase the tendency to restoration of the chiral symmetry. At large values of density the account of interaction inside the matter slowers down the restoration of chiral symmetry compared to the gas approximation law. The value of the condensate at the saturation value of density is obtained. 26 refs., 5 figs