= Gamma-five convention without an imaginary unit
{title2=$G=\gamma^0\gamma^1\gamma^2\gamma^3,\quad G^2=-I$}
For the mostly-minus <Minkowski metric>, this product anticommutes with every <gamma matrix> and is anti-Hermitian in the standard representation. The conventional Hermitian <chirality> matrix is $iG$. Nevertheless $\bar\psi G\psi$ is Hermitian, because $\gamma^0G\gamma^0=-G$. Therefore a real interaction coefficient in $-g\phi\bar\psi G\psi$ is compatible with <Hermitian> dynamics and gives the <Feynman vertex> $-igG$.
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