  We discus recent developments in theory of high energy two-body break-up of
few-nucleon systems. The characteristics of these reactions are such that the
hard two-body quasielastic subprocess can be clearly separated from the
accompanying soft subprocesses. We discuss in details the hard rescattering
model(HRM) in which hard photodisintegration develops in two stages. At first,
photon knocks-out an energetic quark which rescatters subsequently with a quark
of the other nucleon. The latter provides a mechanism of sharing the initial
high momentum of the photon between two outgoing nucleons. This final state
hard rescattering can be expressed through the hard NN scattering amplitude.
Within HRM we discuss hard break-up reactions involving D and 3He targets and
demonstrate how these reactions are sensitive to the dynamics of hard pn and pp
interaction. Another development of HRM is the prediction of new helicity
selection mechanism for hard two-body reactions, which was apparently confirmed
in the recent JLab experiment.
