A measurement of the $CP$ asymmetry difference in $\varLambda_{c}^{+} \to pK^{-}K^{+}$ and $p\pi^{-}\pi^{+}$ decays

The difference between the CP asymmetries in the decays Λ$_{c}^{+}$ → pK$^{−}$K$^{+}$ and Λ$_{c}^{+}$ → pπ$^{−}$π$^{+}$ is presented. Proton-proton collision data taken at centre-of-mass energies of 7 and 8 TeV collected by the LHCb detector in 2011 and 2012 are used, corresponding to an integrated luminosity of 3 fb$^{−1}$. The Λ$_{c}^{+}$ candidates are reconstructed as part of the Λ$_{b}^{0}$ → Λ$_{c}^{+}$ μ$^{−}$X decay chain. In order to maximize the cancellation of production and detection asymmetries in the difference, the final-state kinematic distributions of the two samples are aligned by applying phase-space-dependent weights to the Λ$_{c}^{+}$ → pπ$^{−}$π$^{+}$ sample. This alters the definition of the integrated CP asymmetry to A$_{CP}^{wgt}$ (pπ$^{−}$π$^{+}$). Both samples are corrected for reconstruction and selection efficiencies across the five-dimensional Λ$_{c}^{+}$ decay phase space. The difference in CP asymmetries is found to be