  Light-front quantum chromodynamics may lead to an accurate constituent
approximation for the low-energy properties of hadrons. This requires a cutoff
that violates explicit gauge invariance and Lorentz covariance, leading to the
calculation of a renormalized QCD hamiltonian using a similarity
renormalization group. Renormalization repairs broken symmetries, and in
light-front field theory it moves dynamical effects that usually require large
numbers of partons to few-body effective interactions. This has been shown to
work in QED through dominant contributions to the Lamb shift. In QCD
logarithmic confinement arises at second order, and initial bound state
calculations produce reasonable results.
