  Determination of the parameter regime in which two holes in the t-J model
form a bound state represents a long standing open problem in the field of
strongly correlated systems. By applying and systematically improving the exact
diagonalization method defined over a limited functional space (EDLFS), we show
that the average distance between two holes scales as $\langle d \rangle \sim 2
(J/t)^{-1/4}$ for J/t < 0.15, therefore providing strong evidence that two
holes in the t-J model form the bound state for any nonzero J/t. However, the
symmetry of such bound pair in the ground state is p-wave. This state is
consistent with phase separation at finite hole filling, as observed in a
recent study [Maska et al, Phys. Rev. B 85, 245113 (2012)].
