A microscopic approach to fragment momentum distributions in diffractive breakup of Borromean two-neutron halo nuclei is developed, taking into account the correlated structure of the halo continuum. The crucial role of the low-lying three-body resonances and soft modes in determining distribution characteristics is demonstrated.

• Received 15 June 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.908