Clusters of the two-dimensionnal t--J model with 2 holes and up to 26 sites
are diagonalized using a Lanczos algorithm. The behaviour of the binding energy
with system size suggests the existence of a finite critical value of J above
which binding occurs in the bulk. Only the d-wave pair field operator acting on
the Heisenberg GS has a finite overlap with the 2 hole ground state for all the
clusters considered. The related spectral function associated with the
propagation of a d-wave (spin singlet) pair of holes in the antiferromagnetic
background is calculated. The quasiparticle peak at the bottom of the spectrum
as well as some structure appearing above the peak survive with increasing
cluster size. Although no simple scaling law was found for the quasiparticle
weight the data strongly suggest that this weight is finite in the bulk limit
and is roughly proportional to the antiferromagnetic coupling J (for J<1).Comment: Report LPQTH-93/01, 18 pages (REVTEX), 8 postscript files include