https://doi.org/10.1140/epjc/s10052-020-08550-2
Regular Article – Theoretical Physics
Hadronic vacuum polarization and vector-meson resonance parameters from 
1
Helmholtz-Institut für Strahlen- und Kernphysik (Theorie) and Bethe Center for Theoretical Physics, Universität Bonn, 53115, Bonn, Germany
2
Albert Einstein Center for Fundamental Physics, Institute for Theoretical Physics, University of Bern, Sidlerstrasse 5, 3012, Bern, Switzerland
Received:
29
July
2020
Accepted:
13
October
2020
Published online:
26
October
2020
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.
© The Author(s) 2020
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
Funded by SCOAP3
