%0 Journal Article
%A Holz, S.
%A Plenter, J.
%A Xiao, C. W.
%A Dato, T.
%A Hanhart, Christoph
%A Kubis, B.
%A Meißner, U.-G.
%A Wirzba, A.
%T Towards an improved understanding of ${\eta \rightarrow \gamma ^*\gamma ^*}$
%J The European physical journal / C
%V 81
%N 11
%@ 1434-6044
%C Heidelberg
%I Springer
%M FZJ-2021-04254
%P 1002
%D 2021
%X We argue that high-quality data on the reaction e+e−→π+π−η will allow one to determine the doubly-virtual form factor η→γ∗γ∗ in a model-independent way with controlled accuracy. This is an important step towards a reliable evaluation of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. When analyzing the existing data for e+e−→π+π−η for total energies squared k2>1GeV2, we demonstrate that the effect of the a2 meson provides a natural breaking mechanism for the commonly employed factorization ansatz in the doubly-virtual form factor Fηγ∗γ∗(q2,k2). However, better data are needed to draw firm conclusions.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000718113500001
%R 10.1140/epjc/s10052-021-09661-0
%U https://juser.fz-juelich.de/record/902432