Chiral transformations of spin-1 mesons in the non-symmetric vacuum

A new sort of chiral transformations for spin-1 states is obtained as a result of a linearized diagonalization of πa1 mixing in the effective meson Lagrangian. Using this symmetry argument, we argue that there is no physical distinction between such theory and the theory in which a covariant nonlinear diagonalization is used instead. As an illuminating example, the Nambu-Jona-Lasinio type model with the broken SU(2)×SU(2) chiral symmetry in the one-quark-loop approximation is considered.