Light-Meson Distribution Amplitude: Simple Relativistic Model

Abstract

With the basic concepts of the constituent-quark model formulated in the light-cone Fock approach we present a relativistic model of the pion and $\rho$-meson valence-quark structure. We point out that a nonstatic relativistic spin wave function and small transverse size of the valence configuration are essential to reproduce the basic features of the Chernyak-Zhitnitsky amplitudes for the $\pi$ and $\rho$ as they are obtained from QCD sum-rule techniques.