Quantum field theory approach to the vacuum replica in QCD
  Quantum field theory is used to describe the contribution of possible new QCD vacuum replica to hadronic processes. This sigma-like new state has been recently shown to be likely to appear for any realistic four-quark interaction kernel as a consequence of chiral symmetry. The local operator creating the replica vacuum state is constructed explicitly. Applications to physical processes are outlined. 
A.V.Nefediev (IST, Lisbon and ITEP, Moscow), J.E.F.T.Ribeiro (IST,   Lisbon)