Dynamical explanation for the positivity of topological charge fluctuations in QCD

A dynamical explanation for the positivity of the topological charge fluctuation a^-1 = f; d⁴x <0T(FF~(x), FF~(0))0> in QCD is provided. In the presence of an external coupling to topological charge (θFF~ term) the monopoles which condense in the confining phase carry an electric charge which contributes to their self mass and thus raises the vacuum energy. This result also accounts for the (local) stability of the QCD vacuum against spontaneous CP violation.