Adjoint covariant derivative (source code)

= Adjoint covariant derivative

On an adjoint-valued field $X$, the covariant derivative is $D_\mu X=\partial_\mu X+[A_\mu,X]$. If $X\mapsto gXg^{-1}$, then $D_\mu X\mapsto g(D_\mu X)g^{-1}$.