Speaker
Description
Data-driven evaluations of the hadronic light-by-light contribution to the muon anomalous magnetic moment rely critically on precise experimental inputs. This talk presents recent and ongoing measurements from the BESIII experiment specifically targeted to constrain these theoretical frameworks. Utilizing the large $e^+e^-$ datasets collected at the BEPCII collider, we extract single- and double-virtual transition form factors of pseudoscalar, scalar, tensor, and axial states. We emphasize the systematic challenges in the phenomenologically crucial low- to intermediate-$Q^2$ regime. Results of the two-photon production of pseudoscalar states and preliminary results of the two-photon production of pion pairs will be presented along with an outlook on ongoing measurements.