Exclusive semileptonic Lambda_b decays to excited charmed Lambda_c baryons
are investigated at order Lambda_{QCD}/m_Q in the heavy quark effective theory.
The differential decay rates are analyzed for the J^\pi=1/2^- Lambda_c(2593)
and the J^\pi=3/2^- \Lambda_c(2625). They receive 1/m_{c,b} corrections at zero
recoil that are determined by mass splittings and the leading order Isgur-Wise
function. With some assumptions, we find that the branching fraction for
Lambda_b decays to these states is 2.5-3.3%. The decay rate to the helicity \pm
3/2 states, which vanishes for m_Q \to \infty, remains small at order
Lambda_{QCD}/m_Q since 1/m_c corrections do not contribute. Matrix elements of
weak currents between a Lambda_b and other excited Lambda_c states are analyzed
at zero-recoil to order Lambda_{QCD}/m_Q. Applications to baryonic heavy quark
sum-rules are explored.Comment: 27 pages, 1 fig., minor changes, version to appear in Phys.Rev.
