TY  - JOUR
AU  - Holz, Simon
AU  - Hanhart, Christoph
AU  - Hoferichter, Martin
AU  - Kubis, Bastian
TI  - A dispersive analysis of ${\eta '\rightarrow \pi ^+\pi ^-\gamma }$ and ${\eta '\rightarrow \ell ^+\ell ^-\gamma }$
JO  - The European physical journal / C
VL  - 82
IS  - 5
SN  - 1434-6044
CY  - Heidelberg
PB  - Springer
M1  - FZJ-2022-02163
SP  - 434
PY  - 2022
AB  - We present a dispersive representation of the η′ transition form factor that allows one to account, in a consistent way, for the effects of ρ–ω mixing in both the isoscalar and the isovector contributions. Using this formalism, we analyze recent data on η′→π+π−γ to constrain the isovector part of the form factor, individually and in combination with data for the pion vector form factor, which suggests a tension in the ρ–ω mixing parameter. As a first application, we use our results, in combination with the most recent input for the isoscalar part of the form factor, to predict the corresponding spectrum of η′→ℓ+ℓ−γ, in particular we find the slope parameter bη′=1.455(24)GeV−2. With forthcoming data on the latter process, our results establish the necessary framework to improve the evaluation of the η′-pole contribution to the anomalous magnetic moment of the muon using experimental input from both η′ decay channels.
LB  - PUB:(DE-HGF)16
C6  - 35578684
UR  - <Go to ISI:>//WOS:000794907700004
DO  - DOI:10.1140/epjc/s10052-022-10247-7
UR  - https://juser.fz-juelich.de/record/907692
ER  -