scholarly journals Towards a dispersive determination of the η and η′ transition form factors

2018 ◽  
Vol 166 ◽  
pp. 00012 ◽  
Author(s):  
Bastian Kubis

We discuss status and prospects of a dispersive analysis of the η and η′ transition form factors. Particular focus is put on the various pieces of experimental information that serve as input to such a calculation. These can help improve on the precision of an evaluation of the η and η′ pole contributions to hadronic light-by-light scattering in the anomalous magnetic moment of the muon.

2019 ◽  
Vol 218 ◽  
pp. 03001
Author(s):  
Bastian Kubis

We discuss status and prospects of a dispersive analysis of the π0, η, and η ′ transition form factors. Particular focus is put on the various pieces of experimental information that serve as input to such a calculation. These can help improve on the precision of an evaluation of the light pseudoscalar pole contributions to hadronic light-by-light scattering in the anomalous magnetic moment of the muon.**


2020 ◽  
Vol 234 ◽  
pp. 01008
Author(s):  
Andrzej Kupsc

I summarize recent experimental results for two photon production of mesons. These processes include the neutral pion, η and η′ transition form factors and two photon production of pseudoscalar meson pairs. In addition I discuss the related hadronic and radiative processes. All these processes are attracting attention of experiment and theory due their relevance for the hadronic light-by-light contribution to the muon anomalous magnetic moment.


2019 ◽  
Vol 199 ◽  
pp. 02014
Author(s):  
Pablo Sanchez-Puertas ◽  
K. Kampf ◽  
J. Novotný

The radiative corrections to double-Dalitz $({P\rightarrow\overline ll\overline l'l'})$ decays are revisited and completed up to next-to-leading order in QED, finding mild differences with respect to previous studies. These might be relevant for extracting information about the mesons transition form factors, which play an important role in determining the hadronic light-by-light contribution to the anomalous magnetic moment of the muon.


2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Marvin Zanke ◽  
Martin Hoferichter ◽  
Bastian Kubis

Abstract Estimating the contribution from axial-vector intermediate states to hadronic light-by-light scattering requires input on their transition form factors (TFFs). Due to the Landau–Yang theorem, any experiment sensitive to these TFFs needs to involve at least one virtual photon, which complicates their measurement. Phenomenologically, the situation is best for the f1(1285) resonance, for which information is available from e+e− → e+e−f1, f1 → 4π, f1 → ργ, f1 → ϕγ, and f1 → e+e−. We provide a comprehensive analysis of the f1 TFFs in the framework of vector meson dominance, including short-distance constraints, to determine to which extent the three independent TFFs can be constrained from the available experimental input — a prerequisite for improved calculations of the axial-vector contribution to hadronic light-by-light scattering. In particular, we focus on the process f1 → e+e−, evidence for which has been reported recently by SND for the first time, and discuss the impact that future improved measurements will have on the determination of the f1 TFFs.


1990 ◽  
Vol 48 (4) ◽  
pp. 663-671 ◽  
Author(s):  
J. G. Körner ◽  
K. Schilcher ◽  
M. Wirbel ◽  
Y. L. Wu

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