Determination of $|V_{ub}|$ from exclusive baryonic $B$ decays

We use the exclusive baryonic $B$ decays to determine the Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{ub}$. From the relation $|V_{ub}|^2/|V_{cb}|^2=({\cal B}_π/{\cal B}_D){\cal R}_{ff}$ based on $B^-\to p\bar p π^-$ and $\bar B^0\to p\bar p D^0$ decays, where $|V_{cb}|$ and ${\cal B}_π/{\cal B}_D\equiv{\cal B}(B^-\to p\bar p π^-)/{\cal B}(\bar B^0\to p\bar p D^0)$ are the data input parameters, while ${\cal R}_{ff}$ is the one fixed by the $B\to p\bar p$ transition matrix elements, we find $|V_{ub}|=(3.48^{+0.87}_{-0.63}\pm 0.40\pm 0.07)\times 10^{-3}$ with the errors corresponding to the uncertainties from ${\cal R}_{ff}$, ${\cal B}_π/{\cal B}_D$ 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 $\bar B\to π\ell\bar ν_\ell$ and $Λ_b\to pμ^-\bar ν_μ$ decays, but overlaps the one from the inclusive $\bar B\to X_u \ell\bar ν_\ell$ 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.

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