Escaping from controversies in $CP$ violation measurements in charm decays

Abstract

The breaking of the $CP$ symmetry in $D^0$ meson decays has been awaited for a long time. After a set of measurements provided by the LHCb, CDF, and Belle Collaborations leading in march 2012 to combined results that were consistent with no $CP$ violation at a CL of $0.006\%$ suggesting $CP$ violation at $\sim 1\%$ level. Such a potentially large value of $CP$ violation in charm decays has triggered widespread interest from the whole particle physics community to evaluate the implications of such an interesting unexpected results. However, a more recent combination of more up-to-date results in March 2013, has slightly changed the situation, showing that data are consistent with the $CP$ conserving hypothesis at $2.1\%$ CL. I briefly review the method used by the various Collaborations when extracting the quantity $\Delta A_{CP}$ and the relative results. Finally I discuss the need for additional measurements, and present the potential of a time-dependent analysis when looking for $CP$ violation in $D^0$ decays and how this can be used to largely improve the current sensitivity on the mixing phase ${\varphi }_{MIX}$.

Comments: To appear in the proceedings of The 6th International Workshop on Charm Physics (CHARM 2013)