Measurement of 𝐶⁢𝑃 Violation Observables in 𝐷⁺ → 𝐾^−⁢𝐾⁺⁢𝜋⁺ Decays

A search for violation of the charge-parity (𝐶⁢𝑃) 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 𝐶⁢𝑃 conservation is 8.1%. The 𝐶⁢𝑃 asymmetry observables 𝐴𝜙⁢𝜋+𝐶⁢𝑃|𝑆=(0.95±0.4⁢3stat±0.2⁢6syst)×10−3 and 𝐴¯𝐾*0⁢𝐾+𝐶⁢𝑃|𝑆=(−0.26±0.5⁢6stat±0.1⁢8syst)×10−3 are also measured. These results show no evidence of 𝐶⁢𝑃 violation and represent the most sensitive search performed through the phase space of a multibody decay.