Early Run-3 data validation with the LHCb detector and the search for charm CP violation

该项目将基于使用LHCb检测器在Charm部门搜索CP违规(CPV)。第一次观察到魅力强子衰变中的CPV是在2019年，在D0-&gt；KK和D0-&gt；pi-pi衰变中。该项目将使用D0和gt；K pi衰变寻找中性D0介子混合中的CPV，其中D0是由B介子衰变产生的。信号事件的时间线从LHC pp碰撞开始，然后在主顶点处产生B介子。B介子在第二顶点衰变到D*介子和介子之前，会经过一小段距离。然后，D*介子迅速衰变到D0，并伴随着一个软的介子。由于介子和软pion的存在，事件通道被命名为“双标记次级D0->kpi”。这两个伴生粒子上的电荷允许标记D0介子的味道，这对于识别D0衰变的类型是重要的。对于D0介子，末态K-pi+表示为“右符号”，K+pi-表示为“错误符号”。导致前一个终态的过程是一个Cabibbo有利衰变模式D0-&gt；K-pi+和一个可以忽略不计的D0介子分量振荡成它们的反物质粒子D0-bar，然后是一个双重Cabibbo抑制衰变D0-bar-&gt；K-pi+。可以通过两种衰变机制(双抑制D0-&gt；K+pi衰变，或者D0振荡成D0-bar介子，然后是Cabibbo有利的衰变D0-bar-&gt；K+pi-)来产生“错号”态，其中可以引入CPV。研究正确符号模和错误符号模(按D0介子性质分裂)的衰减率将提供D0介子混合参数和Charm区混合中的CPV的测量。除了双标记衰变，我们还将研究包括单标记半轻子B介子衰变的可能性。在这种情况下，B介子直接衰变到D0介子。此外，我们还将研究D0-&gt；K3pi与D0-&gt；Kpi的分枝分数与D0-&gt；KPI之间的比率。这一标准的烛光测量将为大型强子对撞机运行3开始的早期数据验证提供有用的输入。

The project will be based on searches for CP violation (CPV) in the charm sector with the LHCb dectector. The first observation of CPV in decays of charm hadrons was as recent as 2019, in D0 -> K K and D0 -> pi pi decays. The project will search for CPV in neutral D0 meson mixing using D0 -> K pi decays, where the D0 is produced from B-meson decays. The timeline of a signal event begins with the LHC pp collisions, followed by the production of a B meson at the primary vertex. The B meson travels a short distance before decaying at the secondary vertex to a D* meson and a muon. The D* meson then promptly decays to the D0 along with a soft pion. The event channel is named "doubly-tagged secondary D0 -> Kpi" due to the presence of the muon and the soft pion. The charges on these two companion particles allow for tagging of the flavour of the D0 meson, which is important for the identification of the type of decay of the D0. For D0 mesons, the final state K- pi+ is denoted the "right sign" and the K+ pi - is referred to as the "wrong sign". The processes contributing to the former final state are a Cabibbo-favoured decay mode D0-> K- pi+ and a negligible component of D0 mesons oscillating into their antimatter particle D0-bar, followed by a doubly-Cabibbo suppressed decays D0-bar -> K- pi+. The "wrong-sign" state can be produced via two decay mechanisms (doubly-suppressed D0-> K+ pi decay, or D0 oscillating into a D0-bar meson followed by a Cabibbo-favoured decay D0-bar->K+ pi-) where CPV can be introduced. Studying the decay rates of the right sign and wrong sign modes (split by D0 meson flavour) will provide a measurement of the D0 meson mixing parameters and CPV in mixing in the charm sector. As well as the doubly-tagged decays, we will investigate the possibility of including singly-tagged semi-leptonic B-meson decays. In this case, the B meson decays directly to the D0 meson. Then, there is no soft pion present to help tag the D0 flavour.Additionally, we will study the ratio of the branching fractions of D0 -> K3pi to D0 -> Kpi decays with early Run 3 data. This standard candle measurement will provide useful input for the Early data validation at the start of the LHC Run 3.