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

Abstract

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