We explore the possibility of extracting the weak phase γ from pure
tree decays Λb​→Λ(D0,D0ˉ,DCP0​) in a model
independent way. The CP violating weak phase γ can be determined
cleanly, without any hadronic uncertainties, as these decay modes are free from
the penguin pollutions. Furthermore, neither tagging nor time dependent studies
are required to extract the angle γ with these modes.Comment: 12 pages, LaTex, Minor changes in the text, version to appear in
Phys. Rev.