Search for CP violation in D[superscript 0] → π[superscript -] π [superscript +] π [superscript 0] decays with the energy test

Abstract

A search for time-integrated CP violation in the Cabibbo-suppressed decay D[superscript 0] → π[superscript -] π [superscript +] π [superscript 0] is performed using for the first time an unbinned model-independent technique known as the energy test. Using proton–proton collision data, corresponding to an integrated luminosity of 2.0 fb[superscript −1] collected by the LHCb detector at a centre-of-mass energy of √s = 8 TeV, the world's best sensitivity to CP violation in this decay is obtained. The data are found to be consistent with the hypothesis of CP symmetry with a p-value of (2.6±0.5)%.