Comparative study of the scalar- and tensor-meson production in the reaction $γγ^*(Q^2)\to ηπ^0$

Abstract

The prediction of the cross section $σ(γγ^*(Q^2)\to ηπ^0)$ based on the simultaneous description of the Belle data on the $γγ\to ηπ^0$ reaction and the KLOE data on the $ϕ\toηπ^0γ$ decay is presented. The production of the scalar $a_0(980)$ and tensor $a_2(1320)$ is studied in detail. It is shown that the QCD based asymptotics of the $γ^*(Q^2)γ\to a_2(1320)\toηπ^0$ cross section can be reached by the compensation of the contributions of $ρ(770)$ and $ω(782)$ with the contributions of their radial excitations in $Q^2$ channel. At large $Q^2$ the $a_2(1320)$ contribution is expected to be dominant, while at $Q^2=0$ it is similar to the scalars contribution.