From Color Glass to Color Dipoles in high-energy onium--onium scattering

Within the Color Glass formalism, we construct the wavefunction of a high energy onium in the BFKL and large-N_c approximations, and demonstrate the equivalence with the corresponding result in the Color Dipole picture. We propose a simple factorization formula for the elastic scattering between two non-saturated ``color glasses'' in the center-of-mass frame. This is valid up to energies which are high enough to allow for a study of the onset of unitarization via multiple pomeron exchanges. When applied to the high energy onium-onium scattering, this formula reduces to the Glauber-like scattering between two systems of dipoles, in complete agreement with the dipole picture.