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

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.