Search for CP violation in the phase space of D⁰ → π ⁻π⁺π⁰ decays with the energy test

A search for CP violation in D⁰ → π ⁻ π ⁺ π ⁰ decays is reported, using pp collision data collected by the LHCb experiment from 2015 to 2018 corresponding to an integrated luminosity of 6 fb ⁻¹. An unbinned model-independent approach provides sensitivity to local CP violation within the two-dimensional phase space of the decay. The method is validated using the Cabibbo-favoured channel D⁰ → K ⁻ π ⁺ π ⁰ and background regions of the signal mode. The results are consistent with CP symmetry in this decay. [Figure not available: see fulltext.].