Final-state rescattering mechanism in bottom-baryon decays

A bstract The first observation of CP violation in baryon decays was recently reported by the LHCb collaboration in $$ {\Lambda}_b^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>b</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> → pK − π + π − with A CP = (2.45 ± 0.46 ± 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, $$ {\Lambda}_b^0 $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>Λ</mml:mi> <mml:mi>b</mml:mi> <mml:mn>0</mml:mn> </mml:msubsup> </mml:math> → pπ − , pK − , pρ − , pK ∗− and Λ ϕ , 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.