Final-state rescattering mechanism in bottom-baryon decays

Abstract

The first observation of $CP$ violation in baryon decays was recently reported by the LHCb collaboration in $\Lambda_b^0\to pK^-\pi^+\pi^-$ with $A_{CP} = (2.45 \pm 0.46 \pm 0.10)\%$, which inspires the study on baryon non-leptonic decays. In this work, we perform the first calculation of five exclusive non-leptonic decays, $\Lambda^{0}_{b}\to p\pi^{-}, p K^{-},p\rho^{-},pK^{*-}$ and $\Lambda\phi$, within the re-scattering approach. The triangle diagrams at hadron level are calculated in form of loop integrations. It leads to the generation of strong phases, which is essential to the calculation of $CP$ asymmetries. We present numerical results for branching ratios, direct and partial-wave $CP$ asymmetries, decay asymmetry parameters and their associated $CP$ asymmetries. Our results are consistent with the current LHCb experimental data, which indicates the validity and potential of our approach in studying the $CP$ asymmetries of $b$-baryon decays. Most of our results are expected to be tested in future experiments.