Measurement of neutral charm meson mixing and CP violation parameters using D0->K3Pi decays with LHCb Run 2 data

中性粲介子系统是独一无二的，它的混合和衰变是由上型夸克跃迁驱动的，因此它是一个强大的探测器，可以寻找超出标准模型的物理迹象，并补充正在进行的美和介子领域的测量。考虑到非CP对称的贡献，charm系统中的混合由四个参数表征：两个混合参数x (y)，与D0介子质量特征态之间的质量（宽度）差成正比，以及两个CP违和参数|q/p|和phi。本研究项目旨在通过拟合衰变时间和衰变D0->K+pi+pi-pi-的五维相空间分布来测量所有四个参数。仅2015-16年收集的Run 2 LHCb数据样本，将比以前分析的信号样本大得多，具有世界领先的精度。主要的挑战包括选择一个振幅模型来描述cabibbo有利和双cabibbo抑制衰减的相空间依赖性；考虑到在衰减时间和相空间变量上的非均匀效率；了解背景资料。

The neutral charm meson system is unique, with mixing and decay being driven by up-type quark transitions, and so is a powerful probe to search for signs of physics beyond the standard model, and complement ongoing measurements in the beauty and kaon sectors. Allowing for non-CP-symmetric contributions, mixing in the charm system is characterised by four parameters: two mixing parameters x (y), proportional to the mass (width) difference between D0 meson mass eigenstates, and two CP violation parameters |q/p| and phi. This research project aims to measure all four parameters by a fitting to the decay time and five-dimensional phase-space distributions of the decay D0->K+pi+pi-pi-. With the Run 2 LHCb data sample collected in 2015-16 alone, this will be a far larger signal sample than ever previously analysed, giving world-leading precision. Major challenges include picking an amplitude model to describe the phase-space dependence of the Cabibbo-favoured and doubly-Cabibbo-suppressed decays; accounting for non-uniform efficiency over the decay-time and phase-space variables; and understanding the background sources.