Speaker
Description
We assess the theory prediction for $R(s)$ below the charm threshold and address tensions with the existing data, notably with the 2021 BES-III results. We provide an analysis of the theory uncertainty associated with perturbative QCD in the light of renormalon calculus, and show that the perturbative series is well behaved and under good control. We provide a reliable and conservative estimate of the effect of residual quark-hadron duality violation contributions, which are shown to be sizable up to 2.5 GeV, but negligible for higher energies. Small electromagnetic and quark-mass corrections are also considered. Finally, we compare theory and data, both locally and in their contributions to the anomalous magnetic moment of the muon. Theory is compatible with a combination of all of the available experimental data but discrepancies with the BES-III data reach more than 3$\sigma$.
| Are you an early career researcher? | No |
|---|