Anomalous A-dependence of diffractive leptoproduction of radial excitation $ρ'(2S)$

Abstract

We predict a strikingly different $A$ and $Q^{2}$ dependence of quasielastic leptoproduction of the $ρ^{0}(1S)$-meson and its radial excitation $ρ'(2S)$ on nuclei. Whereas for the $ρ^{0}$ production nuclear transparency $T_{A}$ decreases monotonically with $A$, for the $ρ'$ nuclear transparency $T_{A}$ can have the counterintuitive nonmonotonic $A$-dependence, having the minimum for light nuclei, and increasing with $A$ for medium and heavy nuclei. Strong enhancement of the $ρ' /ρ^{0}$ cross section ratio makes nuclear targets the $ρ'$-factory. The origin of the anomalous $A$-dependence is in the interplay of color transparency effects with the nodal structure of the $ρ'$ wave function. The predicted effects take place at moderate $Q^{2}\lsim (2-3)$GeV$^{2}$, which can be explored in high statistics experiments at CEBAF.