Speaker
Description
Despite being one of the most precisely studied observables in particle physics, there remains a discrepancy of 4.2$\sigma$ between the average value of the most recent direct measurements and the prediction within the Standard Model of the anomalous magnetic moment of the muon $a_\mu= (g−2)_\mu/2$. The precision of the prediction is limited by the knowledge of the hadronic contributions, which cannot be determined perturbatively, but depend on input from experiments. One of these contributions is the hadronic Light-by-Light scattering, which depends on the knowledge of transition form factors of light pseudoscalar, scalar, axial, and tensor mesons as well as the coupling of multi-meson systems to two photons, which is accessible in e$^+$e$^-$ collisions.
The BESIII experiment, operated at the BEPCII accelerator in Beijing, China, has collected the world’s largest data sets of e$^+$e$^-$ collisions in the $tau$-charm region between 2 GeV and 5 GeV. The data are ideally suited to measure the momentum dependence of transition form factors at space-like momentum transfers of $Q^2 \approx $1 GeV$^2$, which is of special relevance in the context of $a_\mu$. In this presentation we discuss recent results, ongoing projects, and future prospects of the measurements at the BESIII experiment.
