Impact of saturation on s-channel helicity nonconservation for diffractive vector mesons

As Glauber has shown in 1959, the spin-flip phenomena caused by the conventional spin-orbit interaction do vanish in the scattering off heavy, strongly absorbing nuclei. On the other hand, the origin of the s-channel helicity nonconservation (SCHNC) in diffractive DIS is of the origin different from simple spin-orbit interaction, and here we demonstrate that SCHNC in vector meson production survives strong absorption effects in nuclear targets. The intranuclear absorption often discussed in terms of the saturation effects introduces a new large scale $Q_A^2$ into the calculation of diffractive vector meson production amplitudes. Based on the color dipole approach, we show how the impact of the saturation scale $Q_A^2$ changes from the coherent to incoherent/quasifree diffractive vector mesons.