Updated determination of D 0 - D 0 mixing and C P violation parameters with D 0 → K + π -

Abstract

We report measurements of charm-mixing parameters based on the decay-time-dependent ratio of D0 → Kþπ− to D0 → K−πþ rates. The analysis uses a data sample of proton-proton collisions corresponding to an integrated luminosity of 5.0 fb−1 recorded by the LHCb experiment from 2011 through 2016. Assuming charge-parity (CP) symmetry, the mixing parameters are determined to be x02 ¼ ð3.9 2.7Þ × 10−5, y0 ¼ ð5.28 0.52Þ × 10−3, and RD ¼ ð3.454 0.031Þ × 10−3. Without this assumption, the measurement is performed separately for D0 and D¯ 0 mesons, yielding a direct CP-violating asymmetry AD ¼ ð−0.1 9.1Þ × 10−3, and magnitude of the ratio of mixing parameters 1.00 < jq/pj < 1.35 at the 68.3% confidence level. All results include statistical and systematic uncertainties and improve significantly upon previo