A phenomenological study of helicity amplitudes of high energy exclusive   leptoproduction of the rho meson
  We apply a previously developed scheme to consistently include the twist-3 distribution amplitudes for transversely polarized rho meson in order to evaluate, in the framework of kT factorization, the helicity amplitudes for exclusive leptoproduction of a light vector meson, at leading order in alphaS. We compare our results with high energy experimental data for the ratios of helicity amplitudes T11/T00 and T01/T00 and get a good description of the data. 
I.V.Anikin, A.Besse, D.Yu.Ivanov, B.Pire, L.Szymanowski and S.Wallon
hep-ph hep-ex