Subleading hadronic vacuum polarization contributions to muon $g-2$: $\mu^+\mu^- \rightarrow \gamma^* \rightarrow \pi^0 \gamma^*$

Abstract

We consider the subleading contributions of the hadronic vacuum polarization, involving the $\pi^0\gamma^*\gamma^*$ transition form factor, to the muon anomalous magnetic moment $g-2$. Various models for the form factor, based on hadronic ansatzes and holographic principles, are considered: They are the Wess-Zumino-Witten, vector meson dominance, lowest meson dominance (one and two vector resonances) models, and AdS/QCD. The model parameters are determined by fitting the experimental data for the $e^+ e^- \rightarrow \pi^0 \gamma$ total cross section. We report numerical results of the corrections to the muon $g-2$ that the resulting values of two vector resonances model are of order-of-magntitude smaller than the one obtained from the dispersion relation.