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 ${\bar{B}}^0\to p\bar{p}{\pi }^0({\rho }^0)$ and ${\bar{B}}^0\to p\bar{p}{\pi }^{+}{\pi }^{-}$ decays. We obtain $\mathcal{B}({\bar{B}}^0\to p\bar{p}{\pi }^0)=(5.0\pm 2.1)\times 10^{-7}$, in agreement with current data, and $\mathcal{B}({\bar{B}}^0\to p\bar{p}{\rho }^0)\simeq \mathcal{B}({\bar{B}}^0\to p\bar{p}{\pi }^0)/3$. Furthermore, we find ${\mathcal{A}}_{CP}({\bar{B}}^0\to p\bar{p}{\pi }^0,p\bar{p}{\rho }^0,p\bar{p}{\pi }^{+}{\pi }^{-})=(-16.8\pm 5.4,-12.6\pm 3.0,-11.4\pm 1.9)\%$. With measured branching fractions $\mathcal{B}({\bar{B}}^0\to p\bar{p}{\pi }^0,p\bar{p}{\pi }^{+}{\pi }^{-})\sim \mathcal{O}(10^{-6})$, 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.

Comments: 12 pages, 2 figures, 2 tables, version to be published in EPJC