Model-independent determination of the strong-phase difference between (Formula presented) and (Formula presented) decays

Measurements of the strong-phase difference between (Formula presented) and (Formula presented) are performed in bins of phase space. The study exploits a sample of quantum-correlated (Formula presented) mesons collected by the BESIII experiment in (Formula presented) collisions at a center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of (Formula presented). Here, (Formula presented) denotes a neutral charm meson in a superposition of flavor eigenstates. The reported results are valuable for measurements of the (Formula presented)-violating phase (Formula presented) (also denoted (Formula presented)) in (Formula presented), (Formula presented) decays, and the binning schemes are designed to provide good statistical sensitivity to this parameter. The expected uncertainty on (Formula presented) arising from the precision of the strong-phase measurements, when applied to very large samples of (Formula presented)-meson decays, is around 1.5° or 2°, depending on the binning scheme. The binned strong-phase parameters are combined to give a value of (Formula presented) for the (Formula presented)-even fraction of (Formula presented) decays, which is around 30% more precise than the previous best measurement of this quantity.