Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A dispersive analysis of $\eta'\to\pi^+\pi^-\gamma$ and $\eta'\to
  \ell^+\ell^-\gamma$   We present a dispersive representation of the $\eta'$ transition form factor
that allows one to account, in a consistent way, for the effects of
$\rho$-$\omega$ mixing in both the isoscalar and the isovector contributions.
Using this formalism, we analyze recent data on $\eta'\to \pi^+\pi^-\gamma$ 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 $\rho$-$\omega$ 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
$\eta'\to\ell^+\ell^-\gamma$, in particular we find the slope parameter
$b_{\eta'}=1.455(24)\text{GeV}^{-2}$. With forthcoming data on the latter
process, our results establish the necessary framework to improve the
evaluation of the $\eta'$-pole contribution to the anomalous magnetic moment of
the muon using experimental input from both $\eta'$ decay channels.

15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
6
The categories of this paper are: astro-ph
4
The categories of this paper are: cond-mat
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
27
The categories of this paper are: comp-gas
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
22
The categories of this paper are: chao-dyn