Measurement of D-D-bar mixing using the ratio of lifetimes for the decays D-->K- pi + and K+K-

• Main Authors: Fisher, Peter H. (Contributor), Cowan, Ray Franklin (Contributor), Dujmic, Denis (Contributor), Henderson, Shawn Wesley (Contributor), Sciolla, Gabriella (Contributor), Spitznagel, M. (Contributor), Yamamoto, R. K. (Contributor), Zhao, M. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor)
• Format: Article
• Language: English
• Published: 2010-07-23T20:25:28Z.
• Subjects: Article
• Online Access: Get fulltext

 We measure the rate of D0-D[over-bar] 0 mixing with the observable yCP=(τKpi/τKK)-1, where τKK and τKpi are, respectively, the mean lifetimes of CP-even D0-->K+K- and CP-mixed D0-->K-pi+ decays, using a data sample of 384  fb[superscript -1] collected by the BABAR detector at the SLAC PEP-II asymmetric-energy B Factory. From a sample of D0 and D̅ 0 decays where the initial flavor of the decaying meson is not determined, we obtain yCP=[1.12±0.26(stat)±0.22(syst)]%, which excludes the no-mixing hypothesis at 3.3σ, including both statistical and systematic uncertainties. This result is in good agreement with a previous BABAR measurement of yCP obtained from a sample of D*+-->D0pi+ events, where the D0 decays to K-pi+, K+K-, and pi+pi-, which is disjoint with the untagged D0 events used here. Combining the two results taking into account statistical and systematic uncertainties, where the systematic uncertainties are assumed to be 100% correlated, we find yCP=[1.16±0.22(stat)±0.18(syst)]%, which excludes the no-mixing hypothesis at 4.1σ.