Model-Independent Search for CP Violation in D0 → K− K+ π− π+ and D0 → π− π+ π+ π− Decays

A search for CP violation in the phase-space structures of D0 and anti-D0 decays to the final states K− K+ π− π+ and π− π+ π+ π− is presented. The search is carried out with a data set corresponding to an integrated luminosity of 1.0 fb^−1 collected in 2011 by the LHCb experiment in pp collisions at a centre-of-mass energy of 7 TeV. For the K− K+ π− π+ final state, the four-body phase space is divided into 32 bins, each bin with approximately 1800 decays. The p-value under the hypothesis of no CP violation is 9.1%, and in no bin is a CP asymmetry greater than 6.5% observed. The phase space of the π− π+ π+ π− final state is partitioned into 128 bins, each bin with approximately 2500 decays. The p-value under the hypothesis of no CP violation is 41%, and in no bin is a CP asymmetry greater than 5.5% observed. All results are consistent with the hypothesis of no CP violation at the current sensitivity.