Abstract
We use the exclusive baryonic B decays to determine the Cabibbo-Kobayashi-Maskawa (CKM) matrix element V ub . From the relation |Vub|2/|Vcb|2=(Bπ/BD)Rff based on B-→pp-π- and B-0→pp-D0 decays, where |V cb | and Bπ/BD≡B(B-→pp-π-)/B(B-0→pp-D0) are the data input parameters, while Rff is the one fixed by the B→pp- transition matrix elements, we find |Vub|=(3.48-0.63+0.87±0.40±0.07)×10-3 with the errors corresponding to the uncertainties from Rff, Bπ/BD and |V cb |, respectively. Being independent of the previous results, our determination of |V ub | has the central value close to those from the exclusive B-→πℓν-ℓ and Λb→pμ-ν-μ decays, but overlaps the one from the inclusive B-→Xuℓν-ℓ with the current uncertainties. The extraction of |V ub | in the baryonic B decays is clearly very useful for the complete determination of the CKM matrix elements as well as the exploration of new physics.