High pT azimuthal correlations: Elliptic flow (I)

Initial anisotropy in coord. space (overlap) in non-central collisions translates into final azimuthal asymmetry in momemtum space (transverse to react. plane)
1. Truly collective effect (absent in p+p colls.).
2. “Hard” probe: develops exclusively in first instants of the reaction (t<3 fm/c).

Initial anisotropy in coord. space (overlap) in non-central collisions translates into final azimuthal asymmetry in momemtum space (transverse to react. plane)