Direct CP violation in internal W -emission dominated baryonic B decays

摘要

The observation of CP violation has been experimentally verified in numerous B decays but is yet to be confirmed in final states with half-spin particles. We focus our attention on baryonic B-meson decays mediated dominantly through internal W-emission processes and show that they are promising processes to observe for the first time the CP violating effects in B decays to final states with half-spin particles. Specifically, we study the $$ar{B}^0ightarrow par{p}pi ^0(ho ^0)$$ Bˉ0→ppˉπ0(ρ0) and $$ar{B}^0ightarrow par{p}pi ^+pi ^-$$ Bˉ0→ppˉπ+π- decays. We obtain $$mathcal{B}(ar{B}^0ightarrow par{p}pi ^0)=(5.0pm 2.1)imes 10^{-7}$$ B(Bˉ0→ppˉπ0)=(5.0±2.1)×10-7, in agreement with current data, and $$mathcal{B}(ar{B}^0ightarrow par{p}ho ^0)simeq mathcal{B}(ar{B}^0ightarrow par{p}pi ^0)/3$$ B(Bˉ0→ppˉρ0)?B(Bˉ0→ppˉπ0)/3. Furthermore, we find $$mathcal{A}_{CP}(ar{B}^0ightarrow par{p}pi ^0,par{p}ho ^0,par{p}pi ^+pi ^-) =(-16.8pm 5.4,-12.6pm 3.0,-11.4pm 1.9)%$$ ACP(Bˉ0→ppˉπ0,ppˉρ0,ppˉπ+π-)=(-16.8±5.4,-12.6±3.0,-11.4±1.9)%. With measured branching fractions $$mathcal{B}(ar{B}^0ightarrow par{p}pi ^0,par{p}pi ^+pi ^-)sim mathcal{O}(10^{-6})$$ B(Bˉ0→ppˉπ0,ppˉπ+π-)～O(10-6), we point out that $$mathcal{A}_{CP}sim -(10-20)%$$ ACP～-(10-20)% can be new observables for CP violation, accessible to the Belle II and/or LHCb experiments.