Experimental input from $e^+e^-$ for $a_{\mu}$ light-by-light

Abstract

The anomalous magnetic momentum of the muon, a_{\mu}aμ, has been measured and calculated with a precision up to ~0.50.5 ppm, but there is a 3 to 4 standard deviations between these two values. The uncertainty in the calculation is dominated by the hadronic part, including the hadronic vacuum polarization and the hadronic light-by-light. The meson transition form factors and the helicity amplitudes can be used as input or constraint to the calculation of the hadronic light-by-light contribution. Latest experimental studies of the transition form factors of \pi^{0}π0, \etaη, and \eta^{\prime}η′ and the cross-section of \gamma\gamma^*\to\pi^+\pi^-γγ*→π+π− from e^{+}e^{-}e+e− collider are presented.