Observation of the suppressed $\Lambda_b^0\to D p K^-$ decay with $D\to K^+ \pi^-$ and measurement of its $C\!P$ asymmetry

TL;DR

This paper reports the first observation of the suppressed $\Lambda_b^0 o D p K^-$ decay with $D o K^+\pi^-$ and measures its $C ext{P}$ asymmetry, providing insights into CKM angle $\gamma$ using LHCb data.

Contribution

It presents the first observation of the suppressed decay mode and measures its branching ratio and $C ext{P}$ asymmetry, advancing understanding of $CP$ violation in baryon decays.

Findings

First observation of the suppressed decay mode.

Measured ratio of branching fractions.

Reported $C ext{P}$ asymmetry value.

Abstract

A study of $\Lambda_b^0$ baryon decays to the $DpK^-$ final state is presented based on a proton-proton collision data sample corresponding to an integrated luminosity of 9 fb$^{-1}$ collected with the LHCb detector. Two $\Lambda_b^0$ decays are considered, $\Lambda_b^0\to DpK^-$ with $D\to K^-\pi^+$ and $D\to K^+\pi^-$, where $D$ represents a superposition of $D^0$ and $\overline{D}^0$ states. The latter process is expected to be suppressed relative to the former, and is observed for the first time. The ratio of branching fractions of the two decays is measured, and the $C\!P$ asymmetry of the suppressed mode, which is sensitive to the CKM angle $\gamma$, is also reported.