Study of Bˉ→Λpˉ ρ(ϕ)\bar B\to \Lambda\bar p\,\rho(\phi) and Bˉ→ΛΛˉKˉ∗\bar B\to \Lambda\bar \Lambda \bar K^{*}

We examine the three-body baryonic $\bar B\to {\bf B\bar B'}V$ decays with $V$ vector mesons in the standard model. We can simultaneously explain the recent experimental data on the decays of $B^-\to \Lambda\bar p \,\rho^0$ and $\bar B\to \Lambda\bar \Lambda \bar K^{*}$ based on the QCD counting rules and SU(3) flavor symmetry. We also predict that the decay branching ratios of $\bar B^0\to \Lambda\bar p \,\rho^+$ and $B^-\to \Lambda\bar p \,\phi$ are 3.0 and $1.5\times 10^{-6}$, respectively, which are promising to be observed by BELLE and BABAR at the $B$ factories.Comment: 10 pages, no figur

Determinations of ∣Vcb∣|V_{cb}| and ∣Vub∣|V_{ub}| from baryonic Λb\Lambda_b decays

We extract the Cabibbo-Kobayashi-Maskawa matrix element $V_{cb}$ from the exclusive decays of $\Lambda_b\to \Lambda_c\ell\bar \nu_\ell$ and $\Lambda_b\to \Lambda_c M_{(c)}$ with $M=(\pi^-,K^-)$ and $M_c=(D^-,D^-_s)$, where the branching ratios of $\Lambda_b\to \Lambda M_{(c)}$ 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 $B\to X_c\ell\bar \nu_\ell$ decays. Furthermore, based on the most recent ratio of $|V_{ub}|/|V_{cb}|$ from the exclusive $\Lambda_b$ 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 $B\to X_u\ell\bar \nu_\ell$ decays. We conclude that our determinations of $|V_{cb}|$ and $|V_{ub}|$ from the exclusive $\Lambda_b$ decays favor the inclusive extractions in the $B$ decays.Comment: 8 pages, i figur

Four-body baryonic decays of B→ppˉπ+π−(π+K−)B\to p \bar{p} \pi^+\pi^-(\pi^+K^-) and Λpˉπ+π−(K+K−)\Lambda \bar{p} \pi^+\pi^-(K^+K^-)

We study the four-body baryonic $B\to {\bf B_1 \bar B_2}M_1 M_2$ decays with $\bf B_{1,2}$ ($M_{1,2}$) being charmless baryons (mesons). In accordance with the recent LHCb observations, each decay is considered to proceed through the $B\to M_1 M_2$ transition together with the production of a baryon pair. We obtain that ${\cal B}(B^-\to \Lambda\bar p \pi^+\pi^-)=(3.7^{+1.5}_{-1.0} )\times 10^{-6}$ and ${\cal B}(\bar B^0\to p\bar p \pi^+\pi^-,p\bar p \pi^+ K^-)=(3.0\pm 0.9,6.6\pm 2.4)\times 10^{-6}$, in agreement with the data. We also predict ${\cal B}(B^-\to\Lambda\bar p K^+ K^-)=(3.0^{+1.3}_{-0.9})\times 10^{-6}$, which is accessible to the LHCb and BELLE experiments.Comment: 11 pages, 3 figure