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

TL;DR

This paper investigates CP violation in baryonic B decays mediated by internal W-emission, predicting measurable asymmetries that could be observed in upcoming experiments like Belle II and LHCb.

Contribution

It proposes that baryonic B decays with half-spin particles are promising for observing direct CP violation, providing specific predictions for asymmetries and branching ratios.

Findings

Predicted CP asymmetries of about -10% to -20% in certain baryonic B decays.

Calculated branching ratios consistent with current experimental data.

Identified these decays as promising channels for future CP violation measurements.

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