  The LHCb Collaboration has recently observed two narrow baryon resonances
with beauty. Their masses and decay modes look consistent with the quark model
orbitally excited states Lambda_b(5912) and Lambda*_b(5920), with quantum
numbers J^P=1/2^- and 3/2^-, respectively. We predict the existence of these
states within a unitarized meson-baryon coupled-channel dynamical model, which
implements heavy-quark spin symmetry. Masses, quantum numbers and couplings of
these resonances to the different meson-baryon channels are obtained. We find
that the resonances Lambda^0_b(5912) and Lambda^0_b(5920) are heavy-quark spin
symmetry partners, which naturally explains their approximate mass degeneracy.
Corresponding bottom-strange baryon resonances are predicted at Xi_b(6035.4)
(J^P=1/2^-) and Xi_b(6043.3) (J^P=3/2^-). The two Lambda_b and two Xi_b
resonances complete a multiplet of SU(3)-flavor times heavy-quark spin
symmetry.
