Study of the $f_2(1270)$ and $a_2(1320)$ resonances in $\gamma^*(Q^2)\gamma$ collisions

TL;DR

This paper investigates how the production cross sections of the $f_2(1270)$ and $a_2(1320)$ resonances depend on the photon virtuality $Q^2$ in $ ext{e}^+ ext{e}^-$ collider experiments, highlighting the transition to QCD asymptotic behavior.

Contribution

It provides a detailed analysis of the $Q^2$ dependence of tensor meson production, emphasizing the role of vector meson contributions and their radial excitations in reaching QCD asymptotics.

Findings

Helicity amplitude dominance changes with increasing $Q^2$.

Transition to QCD asymptotics involves vector meson contributions and their excitations.

Results are relevant for high-luminosity collider experiments studying meson production.

Abstract

We discuss studies of the $Q^2$ dependence of the $f_2(1270)$ and $a_2 (1320)$ production cross sections in $\gamma^*(Q^2)\gamma $ collisions at current and coming into operation colliders with a high luminosity. Changing the dominant helicity amplitude occurs in the reactions $\gamma^*(Q ^2)\gamma\to f_2(1270)$ and $\gamma^*(Q^2) \gamma\to a_2(1320)$ with increasing $Q^2$. This is caused by the coming of the QCD asymptotics. It is shown that the transition to the asymptotic behavior of QCD in the amplitudes $\gamma^*(Q^2) \gamma\to f_2(1270),a_2(1320)$ is provided by the compensation of the contributions of ground vector states $\rho$ and $\omega$ in $Q^2$-channel with the contributions of their radial excitations.