Determinations of $|V_{cb}|$ and $|V_{ub}|$ from baryonic $Λ_b$ decays

Abstract

We extract the Cabibbo-Kobayashi-Maskawa matrix element $V_{cb}$ from the exclusive decays of $Λ_b\to Λ_c\ell\bar ν_\ell$ and $Λ_b\to Λ_c M_{(c)}$ with $M=(π^-,K^-)$ and $M_c=(D^-,D^-_s)$, where the branching ratios of $Λ_b\to ΛM_{(c)}$ measured with high precisions have not been used in the previous studies. Explicitly, we find $|V_{cb}|=(44.0\pm 3.5)\times 10^{-3}$, which agrees with the value of $(42.11\pm 0.74)\times 10^{-3}$ from the inclusive $B\to X_c\ell\bar ν_\ell$ decays. Furthermore, based on the most recent ratio of $|V_{ub}|/|V_{cb}|$ from the exclusive $Λ_b$ decays, we obtain $|V_{ub}|=(4.2\pm 0.4)\times 10^{-3}$, which is close to the value of $(4.49\pm 0.24)\times 10^{-3}$ from the inclusive $B\to X_u\ell\bar ν_\ell$ decays. We conclude that our determinations of $|V_{cb}|$ and $|V_{ub}|$ from the exclusive $Λ_b$ decays favor the inclusive extractions in the $B$ decays.