Large CP violation in $\Lambda_b\rightarrow \Lambda D$ decays and extraction of the Cabibbo-Kobayashi-Maskawa angle $\gamma$

TL;DR

This paper predicts large CP violation effects in $ ext{Lambda}_b o ext{Lambda} D$ decays and proposes a new method to extract the CKM angle $ extgamma$ using angular distributions and decay rates.

Contribution

It introduces the first predictions of sizable CP asymmetries in specific baryon decays and a novel approach to determine the CKM angle $ extgamma$ from these processes.

Findings

CP asymmetries up to 50% predicted in $ ext{Lambda}_b$ decays.

New CP-violating observables related to angular distributions identified.

A strategy to extract the CKM angle $ extgamma$ from decay data proposed.

Abstract

Motivated by the first observation of CP violation in $b$-baryon decays, the search for baryonic decays exhibiting large CP violation will be a primary focus in the coming years. We propose that significant CP-violating effects exist in the decay $\Lambda_b \to \Lambda D$, where $D$ denotes a CP eigenstate of the $D^0 - \bar{D}^0$ system. The predicted CP asymmetries for both the CP-even and CP-odd modes can reach magnitudes as large as $50\%$, making these decays promising targets for measurement at the LHCb experiment. Additionally, we predict for the first time several nonzero CP-violating observables associated with angular distribution parameters, providing valuable complementary information in the search for CP violation in baryon decays. Furthermore, we propose a novel strategy to extract the CKM angle $\gamma$ by combining data on angular distribution parameters and decay rates from the relevant channels. We emphasize that $\Lambda_b \rightarrow \Lambda D$ decays are among the most promising candidates for determining $\gamma$ in the baryon sector. Our findings may offer new insights for future theoretical and experimental investigations.