Evidence for CP violation in time-integrated D0 -> h-h+ decay rates

TL;DR

This paper reports evidence of CP violation in D0 meson decays, with a measured asymmetry difference that significantly deviates from CP conservation, using data from the LHCb experiment.

Contribution

First measurement of time-integrated CP violation difference in D0 decays with a 3.5 sigma significance using LHCb data.

Findings

Measured Delta ACP = -0.82% with statistical and systematic uncertainties.

Observed deviation from CP conservation hypothesis at 3.5 standard deviations.

Provides evidence for CP violation in charm meson decays.

Abstract

A search for time-integrated CP violation in D0 -> h-h+ (h=K, pi) decays is presented using 0.62 fb^-1 of data collected by LHCb in 2011. The flavor of the charm meson is determined by the charge of the slow pion in the D*+ -> D0 pi+ and D*- -> D0bar pi- decay chains. The difference in CP asymmetry between D0 -> K-K+ and D0 -> pi-pi+, Delta ACP = ACP(K-K+) - ACP(pi-pi+), is measured to be [-0.82 \pm 0.21(stat.) \pm 0.11(syst.)]%. This differs from the hypothesis of CP conservation by 3.5 standard deviations.