Light-By Scattering Contribution to Muon g - 2

We discuss hadronic light-by-light scattering contribution to the muon anomalous magnetic moment, a_μ = (g_μ - 2)/2 paying particular attention to the consistent matching between the short- and the long-distance behavior of the light-by-light scattering amplitude. Accounting for the short-distance constraints leads to approximately 50% increase in the central value of a_μ LbL, compared to existing estimates.