A fresh look at hadronic light-by-light scattering in the muon g - 2 with the Dyson-Schwinger approach

Using the Dyson-Schwinger and Bethe-Salpeter equations, we calculate the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon a_mensuremath a_mu , using a phenomenological model for the gluon and quark-gluon interaction. We find a_m=(84 ±13)×10^-11ensuremath a_mu=(84 pm 13)times 10^{-11} for meson exchange, and a_m = (107 ±2 ±46)×10^-11ensuremath a_mu = (107 pm 2 pm 46)times 10^{-11} for the quark loop. The former is commensurate with past calculations; the latter much larger due to dressing effects. This leads to a revised estimate of a_m=116 591 865.0(96.6)×10^-11ensuremath a_mu=116 591 865.0(96.6)times 10^{-11} , reducing the difference between theory and experiment to ≃ 1.9s sigma .