Measurement of the Branching Fractions of the Decays $\bar{B}^{0} \to \Lambda_{c}^{+} \bar{p}$ and $B^{-} \to \Lambda_{c}^{+} \bar{p} \pi^{-}$

TL;DR

This paper measures the branching fractions of specific baryonic B decays using a large data sample, observes a threshold enhancement in the invariant mass spectrum, and provides new experimental results on these decay modes.

Contribution

It presents the first precise measurements of the branching fractions for $ar{B}^{0} o \Lambda_{c}^{+} ar{p}$ and $B^{-} o \Lambda_{c}^{+} ar{p} \pi^{-}$ decays, including the ratio of their branching fractions.

Findings

Branching fraction for $ar{B}^{0} o \Lambda_{c}^{+} ar{p}$ measured as $(2.15 imes 10^{-5})$

Branching fraction for $B^{-} o \\Lambda_{c}^{+} ar{p} \\\pi^{-}$ measured as $(3.53 imes 10^{-4})$

Observation of baryon-antibaryon threshold enhancement in the invariant mass spectrum.

Abstract

We present studies of two-body and three-body charmed baryonic B decays in a sample of 232 million $B\bar{B}$ pairs collected with the BABAR detector at the PEP-II $e^+e^-$ storage ring. The branching fractions of the decays $\bar{B}^{0} \to \Lambda_{c}^{+} \bar{p}$ and $B^{-} \to \Lambda_{c}^{+} \bar{p} \pi^{-}$ are measured to be $(2.15 \pm 0.36 \pm 0.13 \pm 0.56) \times 10^{-5}$ and $(3.53 \pm 0.18 \pm 0.31 \pm 0.92)\times10^{-4}$, respectively. The uncertainties quoted are statistical, systematic, and from the $\Lambda_{c}^{+} \to p K^- \pi^+$ branching fraction. We observe a baryon-antibaryon threshold enhancement in the $\Lambda_{c}^{+} \bar{p}$ invariant mass spectrum of the three-body mode and measure the ratio of the branching fractions to be ${\cal B}(B^{-} \to \Lambda_{c}^{+} \bar{p} \pi^{-})/{\cal B}(\bar{B}^{0} \to \Lambda_{c}^{+} \bar{p}) = 16.4 \pm 2.9 \pm 1.4$. These results are preliminary.