Abstract
We investigate the decay of Λ b →Λνν̄ with the polarized baryons of Λ b and Λ. With the most general hadronic form factors, we first study the decay branching ratio and then derive the longitudinal, normal, and transverse polarizations of Λ in terms of the spin unit vectors of Λ b and A Λ the momentum of Λ. A polarization of Λ b is also discussed.