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We derive a full set, and determine the twist, of helicity amplitudes fordiffractive production of light to heavy vector mesons in deep inelasticscattering. For large $Q^{2}$ all helicity amplitudes but the double-flip arecalculable in perturbative QCD and are proportional to the gluon structurefunction of the proton at a similar hard scale. We find a substantial breakingof the $s$-channel helicity conservation which must persist also in realphotoproduction.Comment: 7 pages, 1 postscript figure. Discussion of double-flip updated,  typos corrected, reference to the ZEUS, H1, HERMES presentations at ICHEP-98  adde

Diffractive vector mesons beyond the s-channel helicity conservation