  The heavy baryon \Lambda_{Q} (Q=b or c) can be regarded as composed of a
heavy quark and a scalar light diquark which has good spin and isospin quantum
numbers. In this picture we establish the Bethe-Salpeter (BS) equation for
\Lambda_{Q} to second order in the 1/m_{Q} expansion. With the kernel
containing both the scalar confinement and the one-gluon-exchange terms we
solve the BS equation numerically. The value of the spin-dependant form factor
for the matrix element
<\Lambda_{b}{(v,s)}|\bar{b}\gamma^{\lambda}\gamma_{5}b|\Lambda_{b}(v,s)>,
\epsilon_{b}, which is non-zero at order 1/m^{2}_{b}, is obtained numerically
from our model.
