Saturation and s-channel helicity nonconservation in diffractive DIS

The s-channel helicity conservation in diffractive DIS is known to break down despite the exact conservation of the s-channel helicity of quarks in high energy QCD. It is demonstrate that the s-channel helicity nonconservation in diffractive vector meson production survived strong absorption effects in nuclear targets. The intranuclear absorption often discussed in terms of the saturation effects introduces a new large scale QA2 into the calculation of diffractive vector meson production amplitudes. Based on the color dipole approach it is shown how the saturation scale QA2 changes from the coherent to incoherent/quasifree diffractive vector mesons