Hadronic vacuum polarization and vector-meson resonance parameters from .

We study the reaction based on a dispersive representation of the underlying transition form factor. As a first application, we evaluate the contribution of the channel to the hadronic-vacuum-polarization correction to the anomalous magnetic moment of the muon. We find , in line with evaluations from the direct integration of the data. Second, our fit determines the resonance parameters of and . We observe good agreement with the channel, explaining a previous tension in the mass between and by an unphysical phase in the fit function. Combining both channels we find and for the masses including vacuum-polarization corrections. The mass agrees perfectly with the PDG average, which is dominated by determinations from the channel, demonstrating consistency with and . For the mass, our result is consistent but more precise, exacerbating tensions with the mass extracted via isospin-breaking effects from the channel.