The s-channel helicity conservation (SCHC) in diffractive DIS is known to break down despite the exact conservation of the s-channel helicity of quarks in high energy QCD. Here we demonstrate that the s-channel helicity nonconservation (SCHNC) in diffractive vector meson production survives strong absorption effects in nuclear targets. This must be contrasted to the classic 1959 result of Glauber that the spin-flip phenomena caused by the conventional spin-orbit interaction do vanish in the scattering off heavy, strongly absorbing nuclei. The intranuclear absorption often discussed in terms of the saturation effects introduces a new large scale Q_A² into the calculation of diffractive vector meson production amplitudes. Based on the color dipole approach, we show how the impact of the saturation scale Q_A² changes from the coherent to incoherent/quasifree diffractive vector mesons.

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