Abstract
We propose a novel method to measure flavor-oscillations and charge-parity (CP) violation in charm mixing. The approach uses multibody charm decays, such as $D^0\to K_S^0\pi^+\pi^-$, and avoids the need for a fit of the decay amplitudes while suppressing biases due to nonuniform signal-reconstruction efficiencies as functions of phase space and decay time. Data are partitioned in decay-time and Dalitz-plot regions (bins). The Dalitz-plot bins are symmetric with respect to the principal bisector and chosen to ensure nearly constant values of the strong-interaction phases in each. The ratios of signal yields observed in each symmetric bin pair are fit as functions of decay time, using independent auxiliary measurements of the strong-interaction phases as constraints, to determine the relevant physics parameters. Simulation shows that this approach improves the sensitivity to the normalized charm-eigenstate mass difference by 35% with respect to existing model-independent methods. In addition, we introduce a parametrization of oscillation and CP-violation effects in charm mixing that has attractive statistical properties and may find wider applicability.
Highlights
The noncoincidence of mass and flavor eigenstates of neutral flavored mesons results in flavor oscillations, which are meson–antimeson transitions that follow an oscillating pattern as a function of time
We propose a novel approach for measuring parameters of oscillation and CP violation in charm mixing using
Ratios of decay yields observed in regions (“bins”) of the Dalitz plot that are symmetric about its bisector are constructed as functions of decay time
Summary
The noncoincidence of mass and flavor eigenstates of neutral flavored mesons results in flavor oscillations, which are meson–antimeson transitions that follow an oscillating pattern as a function of time. D0 → K0Sπþπ−, or other multibody neutral-charm decays, that requires neither an amplitude analysis of the Dalitzplot distribution nor an accurate modeling of the efficiency variations as functions of decay time and Dalitz-plot position. Ratios of decay yields observed in regions (“bins”) of the Dalitz plot that are symmetric about its bisector are constructed as functions of decay time These functions depend on the known hadronic parameters, dependent on Dalitz-plot bin, that enter the GGSZ method to determine γ [20].
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