Measurement of branching fractions and $CP$ asymmetries in $\mathit{\Lambda}_b^0(\mathit{\Xi}_b^0)\!\to pK_{\mathrm S}^0h^-$ decays

TL;DR

This paper reports the first observation of certain baryon decays, measures their branching fractions and $CP$ asymmetries, and finds no evidence of $CP$ violation in these processes using LHCb data.

Contribution

First observation of $ ext{Λ}_b^0$ and $ ext{Ξ}_b^0$ decays to specific final states, with measurements of branching fractions and $CP$ asymmetries, expanding understanding of baryon decay properties.

Findings

First observation of $ ext{Λ}_b^0 o pK_S^0K^-$ and $ ext{Ξ}_b^0 o pK_S^0K^-$ decays.

Measured branching fractions for multiple decay modes.

No evidence of $CP$ violation found in the studied decays.

Abstract

A study of $\mathit{\Lambda}_b^0$ and $\mathit{\Xi}_b^0$ baryon decays to the final states $pK_{\mathrm S}^0\pi^-$ and $pK_{\mathrm S}^0K^-$ is performed using $pp$ collision data collected by the LHCb experiment, corresponding to an integrated luminosity of $9\,\mathrm{fb}^{-1}$. The decays $\mathit{\Lambda}_b^0\!\to pK_{\mathrm S}^0K^-$ and $\mathit{\Xi}_b^0\!\to pK_{\mathrm S}^0K^-$ are observed for the first time, with significances reaching eight standard deviations. The branching fractions and integrated $CP$ asymmetries are measured for the $\mathit{\Lambda}_b^0\!\to pK_{\mathrm S}^0\pi^-$, $\mathit{\Lambda}_b^0\!\to pK_{\mathrm S}^0K^-$, and $\mathit{\Xi}_b^0\!\to pK_{\mathrm S}^0K^-$ decays. For the decay $\mathit{\Lambda}_b^0\!\to pK_{\mathrm S}^0\pi^-$, the $CP$ asymmetries are measured in different regions of the Dalitz plot. No evidence of $CP$ violation is observed.