Angular Analysis of D⁰ → π⁺π⁻μ⁺μ⁻ and D⁰ → K⁺K⁻μ⁺μ⁻ Decays and Search for CP Violation

The first full angular analysis and an updated measurement of the decay-rate CP asymmetry of the D⁰ → π⁺π⁻μ⁺μ⁻ and D⁰ → K⁺K⁻μ⁺μ⁻ decays are reported. The analysis uses proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV. The dataset corresponds to an integrated luminosity of 9  fb⁻¹. The full set of CP -averaged angular observables and their 𝐶⁢𝑃 asymmetries are measured as a function of the dimuon invariant mass. The results are consistent with expectations from the standard model and with CP symmetry.