Three-body baryonic $\overline B\to \Lambda \bar p \pi$ decays and such

Abstract.

We study the decay rates and spectra of $\overline B\to \Lambda \bar p \pi$, $\Sigma^0 \bar p \pi$, $\Sigma^- \bar n \pi$, $\Xi^0 \overline \Sigma {}^+ \pi$, $\Xi^- \overline \Sigma {}^0 \pi$ and $\Xi^- \overline \Lambda \pi$ modes in the factorization approach. The baryon pairs are produced through vector, axial vector, scalar and pseudoscalar operators. Previous predictions, including ours, are an order of magnitude too small compared to experiment. By incorporating QCD counting rules and studying the asymptotic behavior, we find an earlier relation between the pseudoscalar and axial vector form factors to be too restrictive. Instead, the pseudoscalar and scalar form factors are related asymptotically. Following this approach, the measured $\Lambda \bar p \pi^+$ rate ($\sim 4.0 \times 10^{-6}$) and spectrum can be understood, and $\Lambda$ should be dominantly left-hand polarized, while we expect $\cal B(\Sigma^0 \bar p \pi^+)\simeq 1.6\times 10^{-6}$. These results and other predictions can be checked soon.