Measurement of D[superscript 0]–[line over D][subscript 0] Mixing Parameters and Search for CP Violation Using D[subscript 0] → K[subscript +]π[subscript -] Decays

Abstract

Measurements of charm mixing parameters from the decay-time-dependent ratio of D[superscript 0] → K[superscript +]π[superscript −] to D[superscript 0] → K[superscript −]π[superscript +] rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb[superscript −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[superscript '2] = (5.5 ± 4.9) × 10[superscript −5], y[superscript ′] = (4.8 ± 1.0) × 10[superscript −3], and R[subscript D] = (3.568 ± 0.066) × 10[superscript −3]. Allowing for CP violation, the measurement is performed separately for D[superscript 0] and [line over D][superscript 0] mesons yielding A[subscript D] = (−0.7 ± 1.9)%, for the direct CP-violating asymmetry, and 0.75 < |q/p| < 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.