  We study the bound states of two spin-$\half$ fermions interacting via a
contact attraction (characterized by a scattering length) in the singlet
channel in 3D space in presence of a uniform non-Abelian gauge field. The
configuration of the gauge field that generates a Rashba type spin-orbit
interaction is described by three coupling parameters $(\lambda_x, \lambda_y,
\lambda_z)$. For a generic gauge field configuration, the critical scattering
length required for the formation of a bound state is {\em negative}, i.e.
shifts to the "BCS side" of the resonance. Interestingly, we find that there
are special high-symmetry configurations (e.g., $\lambda_x = \lambda_y =
\lambda_z$) for which there is a two body bound state for {\em any} scattering
length however small and negative. Remarkably, the bound-state wave functions
obtained for such configurations have nematic spin structure similar to those
found in liquid $^3$He. Our results show that the BCS-BEC crossover is
drastically affected by the presence of a non-Abelian gauge field. We discuss
possible experimental signatures of our findings both at high and low
temperatures.
