Calculation of the pion-photon transition form factor using dispersion relations and renormalization-group summation

We consider the light cone sum-rule description of the pion-photon transition form factor, based
on dispersion relations, in combination with the renormalization group of QCD, in terms of the formal
solution of the Efremov-Radyushkin-Brodsky-Lepage evolution equation, and show that the emerging
scheme amounts to a certain version of fractional analytic perturbation theory (FAPT). In order to
ensure the correct asymptotic behavior of the considered physical quantity, this modified FAPT version
has to be supplemented by process-specific boundary conditions—in contrast to the standard one.
However, it provides the advantage of significantly improving the inclusion of radiative corrections in the
low-momentum regime of QCD perturbation theory using renormalization-group summation.