Hadronic light-by-light scattering contribution to the muon magnetic   anomaly: constituent quark loops and QCD effects
  The hadronic light-by-light scattering contribution to the muon anomalous magnetic moment can be estimated by computing constituent quark loops. Such an estimate is very sensitive to the numerical values of the constituent quark masses. These can be fixed by computing the hadronic vacuum polarization contribution to the muon magnetic anomaly within the same model. In this Letter, we demonstrate the stability of this framework against first-order perturbative QCD corrections. 
Radja Boughezal, Kirill Melnikov
hep-ph