$CP$ phase structure of QCD from functional renormalization group

Yuepeng Guan, Shinya Matsuzaki, Masatoshi Yamada

We study the low-energy properties of QCD-like theories in the presence of a $P$-odd and $U(1)$ axial breaking four-fermion operator $\left( \barψ ψ\right) \left( \barψ i γ_5 Ï…