Search for CP violation in the phase space of D0→π+π−π+π−decays

Abstract

A search for time-integrated CPviolation in the Cabibbo-suppressed decay D0→π+π−π+π−is performed using an unbinned, model-independent technique known as the energy test. This is the first application of the energy test in four-body decays. The search is performed for P-even CPasymmetries and, for the first time, is extended to probe the P-odd case. Using proton–proton collision data corresponding to an integrated luminosity of 3.0fb−1collected by the LHCb detector at centre-of-mass energies of √s=7TeVand 8TeV, the world’s best sensitivity to CPviolation in this decay is obtained. The data are found to be consistent with the hypothesis of CPsymmetry with a p-value of (4.6 ±0.5)%in the P-even case, and marginally consistent with a p-value of (0.6 ±0.2)%in the P-odd case, corresponding to a significance for CPnon-conservation of 2.7 standard deviations.