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

TL;DR

This paper predicts the cross section for ta meson production in photon-photon interactions, combining experimental data and QCD theory to analyze scalar and tensor meson contributions across different momentum transfer regimes.

Contribution

It provides a unified description of experimental data on ta production and demonstrates how QCD asymptotics are approached through meson contribution compensation.

Findings

QCD asymptotics can be achieved by balancing meson contributions.

At high Q^2, tensor meson a_2(1320) dominates.

At Q^2=0, scalar and tensor contributions are comparable.

Abstract

The prediction of the cross section $\sigma(\gamma\gamma^*(Q^2)\to \eta\pi^0)$ based on the simultaneous description of the Belle data on the $\gamma\gamma\to \eta\pi^0$ reaction and the KLOE data on the $\phi\to\eta\pi^0\gamma$ 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 $\gamma^*(Q^2)\gamma\to a_2(1320)\to\eta\pi^0$ cross section can be reached by the compensation of the contributions of $\rho(770)$ and $\omega(782)$ 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.