CP VIOLATION IN THE D0 → π+π- DECAY AT CDF

摘要

We report a measurement of the CP violating asymmetry in D~(0) → π~(+)π~(-) decays using approximately 215,000 decays reconstructed in about 5.94 fb~(-1) of CDF data. We use the strong D~(?+) → D~(0)π~(+) decay ("D~(?) tag") to identify the flavor of the charmed meson at production time and exploit CP-conserving strong pair-production in collisions. Higher statistic samples of Cabibbo-favored D~(0) → K~(-)π~(+) decays with and without D~(?) tag are used to highly suppress systematic uncertainties due to detector effects. The result, A_(CP)(D~(0) → π~(+)π~(-)) = [0.22 ± 0.24 (stat.) ± 0.11 (syst.)]%, is the world's most precise measurement to date and it is fully consistent with no CP violation.