Zero-sound condensate in a Fermi liquid

Abstract

We consider a normal Fermi liquid with a local scalar interaction given by the Landau parameter f0. The system becomes unstable for f0 < −1 against a growth of scalar-mode excitations (Pomeranchuk instability). We show that the instability may be tamed by the formation of a static Bose condensate of the scalar modes. We study a possible reconstruction of the isospin-symmetric nuclear matter owing to the appearance of the condensate. Possibility of a novel metastable state at subnuclear densities is demonstrated.