  Hadronic form factors for the rare weak transitions
$\Lambda_{b}\rightarrow\Lambda^{(*)}$ are calculated using a nonrelativistic
quark model. The form factors are extracted in two ways. An analytic extraction
using single component wave functions (SCA) with the quark current being
reduced to its nonrelativistic Pauli form is employed in the first method. In
the second method, the form factors are extracted numerically using the full
quark model wave function (MCN) with the full relativistic form of the quark
current. Although there are differences between the two sets of form factors,
both sets satisfy the relationships expected from the heavy quark effective
theory (HQET). Differential decay rates, branching ratios and forward-backward
asymmetries (FBAs) are calculated for the dileptonic decays
$\Lambda_{b}\rightarrow\Lambda^{(*)}\ell^{+}\ell^{-}$, for transitions to both
ground state and excited daughter baryons. Inclusion of the long distance
contributions from charmonium resonances significantly enhances the decay
rates. In the MCN model the $\Lambda(1600)$ mode is the dominant mode in the
$\mu$ channel when charmonium resonances are considered; the $\Lambda(1520)$
mode is also found to have a comparable branching ratio to that of the ground
state in the $\mu$ channel.
