The Wilson loop in light-front quantization
  Using Dirac's method for the quantization of constrained systems QED is canonically quantized in the front-form in a gauge which is the light-front analog of the Weyl gauge. From the obtained vacuum wave functional the spatial Wilson loop is calculated. The result known from the canonical instant-form quantization or from the covariant path integral quantization is found only if the static limit $x^+ \to 0$ is taken in a specific order. The same ambiguity is also found in the static photon propagator in coordinate space. 
Hugo Reinhardt
hep-th