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

Abstract

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 bar{B}^0rightarrow pbar{p}pi ^0(rho ^0) and bar{B}^0rightarrow pbar{p}pi ^+pi ^- decays. We obtain mathcal{B}(bar{B}^0rightarrow pbar{p}pi ^0)=(5.0pm 2.1)times 10^{-7}, in agreement with current data, and mathcal{B}(bar{B}^0rightarrow pbar{p}rho ^0)simeq mathcal{B}(bar{B}^0rightarrow pbar{p}pi ^0)/3. Furthermore, we find mathcal{A}_{CP}(bar{B}^0rightarrow pbar{p}pi ^0,pbar{p}rho ^0,pbar{p}pi ^+pi ^-) =(-16.8pm 5.4,-12.6pm 3.0,-11.4pm 1.9)%. With measured branching fractions mathcal{B}(bar{B}^0rightarrow pbar{p}pi ^0,pbar{p}pi ^+pi ^-)sim mathcal{O}(10^{-6}), we point out that mathcal{A}_{CP}sim -(10-20)% can be new observables for CP violation, accessible to the Belle II and/or LHCb experiments.