  We compute radiative corrections to $\Lambda_b \to \Lambda$ from factors, at
next-to-leading logarithmic accuracy, from QCD light-cone sum rules with
$\Lambda_b$-baryon distribution amplitudes. Employing the diagrammatic approach
factorization of the vacuum-to-$\Lambda_b$-baryon correlation function is
justified at leading power in $\Lambda/m_b$, with the aid of the method of
regions. Hard functions entering the factorization formulae are identical to
the corresponding matching coefficients of heavy-to-light currents from QCD
onto soft-collinear effective theory. The universal jet function from
integrating out the hard-collinear fluctuations exhibits richer structures
compared with the one involved in the factorization expressions of the
vacuum-to-$B$-meson correlation function. Based upon the QCD resummation
improved sum rules we observe that the perturbative corrections at ${\cal
O}(\alpha_s)$ shift the $\Lambda_b \to \Lambda$ from factors at large recoil
significantly and the dominant contribution originates from the next-to-leading
order jet function instead of the hard coefficient functions. Having at hand
the sum rule predictions for the $\Lambda_b \to \Lambda$ from factors we
further investigate several decay observables in the electro-weak penguin
$\Lambda_b \to \Lambda \, \ell^{+} \ell^{-}$ transitions in the factorization
limit (i.e., ignoring the "non-factorizable" hadronic effects which cannot be
expressed in terms of the $\Lambda_b \to \Lambda$ from factors), including the
invariant mass distribution of the lepton pair, the forward-backward asymmetry
in the dilepton system and the longitudinal polarization fraction of the
leptonic sector.
