Measurement of CP asymmetries in $D^0 \rightarrow hh$ decays

TL;DR

This paper reports the most precise measurements to date of time-integrated CP asymmetries in $D^0 ightarrow hh$ decays, using LHCb data, finding no evidence of CP violation.

Contribution

It provides the most precise single-experiment measurements of CP asymmetries in charm decays, combining prompt and secondary decays at 7 and 8 TeV.

Findings

Measured $A_{CP}(K^-K^+)$ and $A_{CP}(\pi^-\pi^+)$ with unprecedented precision.

Results show no evidence of CP asymmetry in these decay modes.

Sets new constraints on CP violation in the charm sector.

Abstract

The latest measurements of the individual time-integrated CP asymmetry in the Cabibbo-suppressed decays $D^0\rightarrow hh$ decays are presented. The results are based on $pp$ collision data, corresponding to an integrated luminosity of $3 fb^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. A combination of the asymmetries using both prompt and secondary charm decays is presented $A_{CP}(K^-K^+) = (0.04 \pm 0.12(stat) \pm 0.10(syst))%$; $A_{CP}(\pi^-\pi^+) = (0.07 \pm 0.14(stat) \pm 0.11(syst))$. These are the most precise measurements from a single experiment. The result for $A_{CP}(K^-K^+)$ is the most precise determination of a time-integrated CP asymmetry in the charm sector to date, and neither measurement shows evidence of CP asymmetry.