Unbinned model-independent measurements with coherent admixtures of multibody neutral D meson decays

Various studies of Standard Model parameters involve measuring the properties of a coherent admixture of D 0 and D ¯ 0 states. A typical example is the determination of the Unitarity Triangle angle γ in the decays B → D K , D → K S 0 π + π - . A model-independent approach to perform this measurement is proposed that has superior statistical sensitivity than the well-established method involving binning of the D → K S 0 π + π - decay phase space. The technique employs Fourier analysis of the complex phase difference between D 0 and D ¯ 0 decay amplitudes and can easily be generalised to other similar measurements, such as studies of charm mixing or determination of the angle β from B 0 → D h 0 decays.