Anisotropic flows from initial state of a fast nucleus

We analyze azimuthal anisotropy in heavy-ion collisions related to the reaction plane in terms of the standard reggeon approach and find that it is non-zero even when the final-state interaction is switched off. This effect can be interpreted in terms of the partonic structure of the colliding nuclei. We use a Feynman diagram analysis to describe the details of this mechanism. The main qualitative features of the appropriate azimuthal correlations are discussed. (orig.)