The one-body partonic distributions in the hadrons are well investigated using electromagnetic
or weak interactions. The events with multiple electromagnetic or weak interactions
on the same hadron are the very rare. Thus the double parton distributions can be investigated
in the events with double QCD hard scattering of partons of the same hadron:
it depends not only on the rapidities (or fractional momenta) of the partons but also on
a transverse variable. The nucleon-deuteron collision can be a good candidate for this
kind of investigations because of the known structure of the deuteron wave function which
provides a probe, absent in hadron-hadron collision.
