BIASED DISCRETE SYMMETRY-BREAKING AND FERMI BALLS

The spontaneous breaking of an approximate discrete symmetry is consid ered, with the resulting protodomains of true and false vacuum being s eparated by domain walls. Given a strong, symmetric Yukawa coupling of the real scalar field to a generic fermion, the domain walls accumula te a gas of fermions, which modify the domain wall dynamics. The split ting of the degeneracy of the ground states results in the false vacuu m protodomain structures eventually being fragmented into tiny false v acuum bags with a Fermi gas shell (Fermi balls), that may be cosmologi cally stable due to the Fermi gas pressure and wall curvature forces, acting on the domain walls. As fermions inhabiting the domain walls do not undergo number density freeze out, stable Fermi balls exist only if a fermion anti-fermion asymmetry occurs. Fermi balls formed with a new Dirac fermion that possesses no standard model gauge charges provi de a novel cold dark matter candidate.