Role of axial-vector mesons near the chiral phase transition

We present a systematic study of the vector-axial-vector mixing (V-A mixing) in the current correlation functions and its evolution with temperature within an effective field theory. The a1-ρ-π coupling vanishes at the critical temperature Tc and thus the V-A mixing also vanishes. A remarkable observation is that even for finite mπ the ρ and a1 meson masses are almost degenerate at Tc. The vanishing V-A mixing at Tc stays approximately intact.