  We review the Hadronic Light-by-Light (HLbL) contribution to the muon
anomalous magnetic moment. Upcoming measurements will reduce the experimental
uncertainty of this precision observable by a factor of four, thus breaking the
current balance with the theoretical prediction. A necessary step to restore it
is to decrease the HLbL contribution error, which implies a study of the
high-energy intermediate states that are neglected in dispersive estimates. We
focus on the maximally symmetric high-energy regime and in quark loop
approximation of perturbation theory we check the
kinematic-singularity/zero-free tensor decomposition of the HLbL amplitude.
