Production of spin-3 mesons in diffractive DIS

Abstract

We calculate the amplitudes of J PC = 3- - meson production in diffractive DIS within the kt-factorization approach, with particular attention paid to the $\rho_3(1690)$ meson. We find that at all Q2 the $\rho_3(1690)$ production cross section is 2-5 times smaller than the $\rho(1700)$ production cross section, which is assumed to be a pure D-wave state. Studying $\sigma_{\mathrm{L}}$ and $\sigma_{\mathrm{T}}$ separately, we observe domination of $\rho_3$ in $\sigma_{\mathrm{L}}$ and domination of $\rho(1700)$ in $\sigma_{\mathrm{T}}$ and offer an explanation of this behavior in simple terms. We also find very strong contributions - sometimes even domination - of the s-channel helicity violating amplitudes. The typical color dipole sizes probed in $\rho_3$ production are shown to be larger than those in the ground state $\rho$ production, and the energy dependence of $\rho_3$ cross section turns out to be much flatter than the $\rho$ production cross section. All the conclusions about the relative behavior of the $\rho_3(1690)$ and $\rho(1700)$ mesons are numerically stable against variations of the input parameters.