Violation of PCAC and two-body baryonic $B$ and $D_s$ decays

TL;DR

This paper investigates two-body baryonic decays of $B$ and $D_s$ mesons, demonstrating that the violation of PCAC at the GeV scale significantly impacts decay mechanisms and branching ratios, aligning predictions with experimental data.

Contribution

It introduces a model based on the annihilation mechanism that accounts for PCAC violation at the GeV scale, providing accurate predictions for baryonic decay branching ratios.

Findings

Predicted branching ratios match experimental data.

Explained ${ m B}(ar B^0_{(s)} o par p)$ and ${ m B}(D_s^+ o par n)$.

Predicted measurable decay modes for future experiments.

Abstract

We study the two-body baryonic $B$ and $D_s$ decays based on the annihilation mechanism without the partial conservation of axial-vector current (PCAC) at the GeV scale. We demonstrate that the contributions of $B^-\to \Lambda\bar p$, $B^-\to \Sigma^0 \bar p$ and $\bar B^0_s\to \Lambda\bar \Lambda$ are mainly from the scalar and pseudoscalar currents with their branching ratios predicted to be around $(3.5,\,5.3,\,5.3)\times 10^{-8}$, respectively, exactly the sizes of ${\cal B}(B\to {\bf B\bar B'})$ established by the data. We also apply the annihilation mechanism to all of the charmless two-body baryonic $B$ and $D_s$ decays. In particular, we can explain ${\cal B}(\bar B^0_{(s)}\to p\bar p)$ of order $10^{-8}$ and ${\cal B}(D_s^+\to p\bar n)$ of order $10^{-3}$, which are from the axial-vector currents. In addition, the branching ratios of $\bar B^0\to \Lambda\bar \Lambda$, $B^-\to n\bar p$, and $B^-\to \Sigma^- \bar\Sigma^0$ are predicted to be $(0.3,\,3.2,\,9.6)\times 10^{-8}$, which can be measured by LHCb and viewed as tests for the violation of PCAC at the GeV scale.