Measurement of CP Violation Observables in D^{+}→K^{-}K^{+}π^{+} Decays.

A search for violation of the charge-parity (CP) symmetry in the D^{+}→K^{-}K^{+}π^{+} decay is presented, with proton-proton collision data corresponding to an integrated luminosity of 5.4  fb^{-1}, collected at a center-of-mass energy of 13 TeV with the LHCb detector. A novel model-independent technique is used to compare the D^{+} and D^{-} phase-space distributions, with instrumental asymmetries subtracted using the D_{s}^{+}→K^{-}K^{+}π^{+} decay as a control channel. The p value for the hypothesis of CP conservation is 8.1%. The CP asymmetry observables A_{CP|S}^{ϕπ^{+}}=(0.95±0.43_{stat}±0.26_{syst})×10^{-3} and A_{CP|S}^{K[over ¯]^{*0}K^{+}}=(-0.26±0.56_{stat}±0.18_{syst})×10^{-3} are also measured. These results show no evidence of CP violation and represent the most sensitive search performed through the phase space of a multibody decay.