Measurement of $CP$ asymmetries in ${\mathrm{\Lambda }}_b^0\to p{h}^{-}$ decays

A search for $CP$ violation in ${\mathrm{\Lambda }}_b^0\to p{K}^{-}$ and ${\mathrm{\Lambda }}_b^0\to p{\pi }^{-}$ decays is presented using the full Run 1 and Run 2 data samples of $pp$ collisions collected with the LHCb detector, corresponding to an integrated luminosity of 9 ${\mathrm{f}\mathrm{b}}^{-1}$ at center-of-mass energies of 7, 8, and 13 TeV. For the Run 2 data sample, the $CP$-violating asymmetries are measured to be $A_{CP}^{p{K}^{-}}=(-1.4\pm 0.7\pm 0.4)\mathrm{\%}$ and $A_{CP}^{p{\pi }^{-}}=(0.4\pm 0.9\pm 0.4)\mathrm{\%}$, where the first uncertainty is statistical and the second is systematic. Following significant improvements in the evaluation of systematic uncertainties compared to the previous LHCb measurement, the Run 1 dataset is reanalyzed to update the corresponding results. When combining the Run 2 and updated Run 1 measurements, the final results are found to be $A_{CP}^{p{K}^{-}}=(-1.1\pm 0.7\pm 0.4)\mathrm{\%}$ and $A_{CP}^{p{\pi }^{-}}=(0.2\pm 0.8\pm 0.4)\mathrm{\%}$, constituting the most precise measurements of these asymmetries to date.