C. Parkes

On the interplay of direct and indirect CP violation in the charm sector

Charm mixing and CP violation observables are examined in light of the recently reported evidence from LHCb for CP violation in the charm sector. If the result is confirmed as being due to direct CP violation at the 1% level, its effect will need to be taken into account in the interpretation of CP violation observables. The contributions of direct and indirect CP violation to the decay rate asymmetry difference ΔACP and the ratios of effective lifetimes AΓ and yCP are considered here. Terms relevant to the interpretation of future high-precision measurements which have been neglected in the previous literature are identified.

Search for matter-antimatter asymmetries in multi-body decays with GPUs

The LHCb experiment has recorded the worlds largest sample of charmed meson decays. The search for matter-antimatter asymmetries in charm sector uses large event samples and requires high precision analysis and thus intensive computing. This paper describes a powerful method to measure matter-antimatter asymmetries in multi-body decays where GPU systems have been successfully exploited. In this method, local asymmetries in the phase-space distributions were explored with an unbinned approach, and the parallelisation of GPU makes this approach usable in practice for the first time. The performance including GPUs on the Grid will be discussed in detail. With this new method, the worlds best sensitivities to particular decay channels have been achieved.