Measurement of the difference of time-integrated CP asymmetries in $D^0 \rightarrow K^{-} K^{+} $ and $D^0 \rightarrow \pi^{-} \pi^{+} $ decays

• Published in: Physical review letters 2016-05, Vol.116
• Main Authors: Aaij, R., Amhis, Y., Barsuk, S., Fleuret, F., Kochebina, O., Lefrançois, J., Li, Y., Machefert, F., Manca, G., Massacrier, L.M., Quagliani, R., Renaudin, V., Robbe, P., Schune, M.-H., Vallier, A., Viaud, B., Wormser, G., Beaucourt, L., Chefdeville, M., Decamp, D., Déléage, N., Ghez, P., Lees, J.P., Marchand, J.F., Minard, M.N., Pietrzyk, B., t'Jampens, S., Tisserand, V., Tournefier, E., Akar, S., Aslanides, E., Cogan, J., De Bruyn, K., Kanso, W., Legac, R., Leroy, O., Mancinelli, G., Martin, M., Mordà, A., Serrano, J., Tayduganov, A., Tsaregorodtsev, A.
• Format: Article
• Language: English
• Subjects: High Energy Physics - Experiment; Physics
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.116.191601

A search for CP violation in $D^0 \rightarrow K^{-} K^{+} $ and $D^0 \rightarrow \pi^{-} \pi^{+} $ decays is performed using $pp$ collision data, corresponding to an integrated luminosity of $3~fb^{-1}$, collected using the LHCb detector at centre-of-mass energies of 7 and $8~$TeV. The flavour of the charm meson is inferred from the charge of the pion in $D^{*+}\rightarrow D^0\pi^+$ and $D^{*-}\rightarrow \bar{D^0}\pi^{-}$ decays. The difference between the CP asymmetries in $D^0 \rightarrow K^{-} K^{+} $ and $D^0 \rightarrow \pi^{-} \pi^{+} $ decays, $\Delta A_{CP} \equiv A_{CP}(K^{-} K^{+}) - A_{CP}(\pi^{-} \pi^{+})$, is measured to be $\left( -0.10 \pm 0.08(stat) \pm 0.03(syst) \right) \%$. This is the most precise measurement of a time-integrated CP asymmetry in the charm sector from a single experiment.