Wilson loop
= Wilson loop
{c}
{title2=$W_\gamma=\operatorname{tr}\mathcal P\exp(-\oint_\gamma A)$}
{wiki}
With <gauge covariant derivative> $D=d+A$, a Wilson loop is the <matrix trace> in a specified <group representation> of <parallel transport> around a closed curve. The <holonomy of a connection> changes by conjugation under <gauge equivalence of principal connections>, so its trace is gauge-invariant. It detects global connection data even when the local <gauge curvature> is zero.