Parity andCTRealization in QCD

We show that an essential assumption in the Vafa-Witten theorem on $P$ and $\mathrm{CT}$ realization in vectorlike theories, the existence of a free energy density in Euclidean space in the presence of any external Hermitian symmetry breaking source, does not apply if the symmetry is spontaneously broken. The assumption that the free energy density is well defined requires the previous assumption that the symmetry is realized in the vacuum. Even if Vafa and Witten's conjecture is plausible, actually a theorem is still lacking.