Hadronic effects in the muon anomalous magnetic moment

We discuss the hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, aμ=(gμ−2)/2, paying particular attention to the consistent matching of the short- and long-distance behaviors of the light-by-light scattering amplitude. Accounting for the short-distance constraints leads to an approximately 50% increase in the central value of aμLbL compared with existing estimates.