Abstract
We start with a brief motivation why the pion transition form factor is interesting and, in particular, how it is related to the high-precision standard-model calculation of the gyromagnetic ratio of the muon. Then we report on the current status of our ongoing project to calculate the pion transition form factor using dispersion theory. Finally we present and discuss a wish list of experimental data that would help to improve the input for our calculations and/or to cross-check our results.
Highlights
As a consequence of these on-going activities it can be expected that the uncertainty in the standard-model prediction originating in the hadronic vacuum-polarization contribution will be significantly reduced in the near future. This development moves the focus to the hadronic contribution to the gyromagnetic ratio of the muon: the hadronic light-by-light scattering contribution depicted in the middle of figure 1
Given the ongoing experimental activities to improve on the direct determination of the gyromagnetic ratio of the muon and on the input for the hadronic vacuum-polarization contribution, it is high time to improve on the standard-model prediction for the hadronic light-by-light scattering contribution including a reliable uncertainty estimate
Note that in the dispersive framework the pion in figure 1 is onshell while the photons in the loops can have arbitrary virtuality; see the corresponding discussion in [6]. This matches with the definition (1) of the pion transition form factor where the pion is an external, i.e. physical state
Summary
This presentation is closely related to the talks by B. As a consequence of these on-going activities it can be expected that the uncertainty in the standard-model prediction originating in the hadronic vacuum-polarization contribution will be significantly reduced in the near future This development moves the focus to the hadronic contribution to the gyromagnetic ratio of the muon: the hadronic light-by-light scattering contribution depicted in the middle of figure 1. Given the ongoing experimental activities to improve on the direct determination of the gyromagnetic ratio of the muon and on the input for the hadronic vacuum-polarization contribution, it is high time to improve on the standard-model prediction for the hadronic light-by-light scattering contribution including a reliable uncertainty estimate. This matches with the definition (1) of the pion transition form factor where the pion is an external, i.e. physical state
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
