Willem Verplanke, "Pseudoscalar transition form factors and the hadronic light-by-light contribution to the muon g-2"

Tuesday Feb 27, 2024, 2:00 PM → 3:00 PM Europe/Paris

210/1-114 - Salle des Séminaires (IJCLab)

The anomalous magnetic moment of the muon has sparked a lot of scientific activity (in the lattice QCD community) due to persistent tensions between the experimental results and the theoretical computations. In view of future experimental precision, the hadronic contributions that enter the theoretical computation of this observable need to be controlled and computed more precisely.

The hadronic contributions that dominate the error budget of the muon $g-2$ are the hadronic vacuum polarization and the hadronic light-by-light (HLbL) scattering. In a dispersive framework, the latter is a sum of contributions from different intermediate states. The most relevant of these are the pseudoscalar-pole contributions, that require knowledge about pseudoscalar transition form factors (TFFs) ($P \to  \gamma^* \gamma^*$, for $P = \pi^0, \eta, \eta'$).

In this talk, we present the first lattice QCD computation of the three pseudoscalar TFFs at the physical point. We then use these TFFs to compute the pseudoscalar-pole contributions to the HLbL scattering in the muon $g-2$. We compare our results with other estimates and give an outlook. We also present our results for the masses and mixing parameters of the $\pi^0, \eta$ and $\eta'$ mesons at the physical point, which are a necessary input to the computation of the TFFs.