On the Wess–Zumino term in high energy QCD

Recently, Kovner and Lublinsky proposed new small-x QCD evolution equations valid when the gluon density inside the target is low. The key element of their construction is the Wess–Zumino term which ensures the non-commutativity of valence charges. In this paper we clarify the origin and significance of this term by showing that it can be naturally incorporated in the effective theory of Color Glass Condensate. We also reexamine the renormalization group description in the high density (JIMWLK) regime.