Measurement of D0-D̄0 mixing parameters and search for CP violation using D0→K+π- decays

Abstract

Measurements of charm mixing parameters from the decay-time-dependent ratio of D0→K+π- to D0→K -π+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb-1 of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP) symmetry, the mixing parameters are determined to be x′2=(5.5±4.9) ×10-5, y′=(4.8±1.0)×10 -3, and RD=(3.568±0.066)×10-3. Allowing for CP violation, the measurement is performed separately for D0 and D̄0 mesons yielding AD=(-0.7±1.9)%, for the direct CP-violating asymmetry, and 0.75 <1.24 at the 68.3% confidence level, for the parameter describing CP violation in mixing. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation. © 2013 CERN. Published by the American Physical Society under the terms of the xlink:href=http://creativecommons.org/licenses/ by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.