A search for time-integrated CP violation in $D^{0} \rightarrow h^{-}h^{+}$ decays

TL;DR

This paper reports a search for time-integrated CP violation in D0 meson decays, finding evidence of CP violation at 3.5 sigma significance, which could indicate physics beyond the Standard Model.

Contribution

First measurement of the difference in CP asymmetry between D0 to K-K+ and pi-pi+ decays using LHCb data, indicating potential new physics effects.

Findings

Measured ΔA_CP = [-0.82 ± 0.21 (stat.) ± 0.11 (syst.)]%

Evidence of CP violation at 3.5 sigma significance

Supports previous hints of CP violation in charm decays

Abstract

The LHCb Collaboration has recently observed evidence of CP violation in neutral D meson decays. CP violation in the charm sector is generically expected to be very small in the Standard Model, but can be enhanced in many models of new physics. In this document we will present the results of a search for time-integrated \CP violation in $D^0 \rightarrow h^- h^+$ with $(h=K,\pi)$ decays, performed with around 0.6 fb$^{-1}$ of data collected by LHCb in 2011. The difference in CP asymmetry between $D^0 \rightarrow K^- K^+$ and $D^0 \rightarrow \pi^- \pi^+$, $\Delta A_{CP} = A_{CP}(K^- K^+) - A_{CP}(\pi^- \pi^+)$ is measured to be $\Delta A_{CP} = [-0.82 \pm 0.21 (stat.) \pm 0.11 (syst.)]%$ . This differs from the hypothesis of CP conservation by 3.5 sigma.