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