Lightest pseudoscalar exchange contribution to light-by-light scattering piece of the muon g − 2

Abstract

Lightest pseudoscalar (P=π0,η,η′) exchange contribution to the light-by-light (LbL) scattering piece of the muon anomaly, aμ=(gμ−2)/2, has been evaluated using a resonance chiral Lagrangian (RχL). Best description of pion transition form-factor (TFF) data is obtained with only tiny violations of one of the relations in the minimal consistent set of short-distance constraints on the anomalous RχL couplings. η(′)TFF, predicted in terms of the πTFF and the η−η′ mixing, are in good agreement with measurements. With this input, we obtain aμP,LbL=(10.47±0.54)⋅10−10, consistent with the reference determinations in the literature, albeit with smaller error.