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

Abstract

We discuss studies of the $Q^2$ dependence of the $f_2(1270)$ and $a_2(1320)$ production cross sections in ${\gamma }^{\ast }(Q^2)\gamma$ collisions at current and coming into operation colliders with a high luminosity. Changing the dominant helicity amplitude occurs in the reactions ${\gamma }^{\ast }(Q^2)\gamma \to f_2(1270)$ and ${\gamma }^{\ast }(Q^2)\gamma \to a_2(1320)$ 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 ${\gamma }^{\ast }(Q^2)\gamma \to f_2(1270),a_2(1320)$ 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.

Comments: 4 pages, 3 figures; typos corrected