ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2014, vol. 112, p. -
Observation of D0 - D̄ 0 Mixing in e+ e- collisions
We observe D0-D̄ 0 mixing in the decay D0→K+π - using a data sample of integrated luminosity 976 fb-1 collected with the Belle detector at the KEKB e +e- asymmetric-energy collider. We measure the mixing parameters x′ 2=(0.09±0.22)×10-3 and y′=(4.6±3.4)×10-3 and the ratio of doubly Cabibbo-suppressed to Cabibbo-favored decay rates RD=(3.53±0.13)×10-3, where the uncertainties are statistical and systematic combined. Our measurement excludes the no-mixing hypothesis at the 5.1 standard deviation level. © 2014 American Physical Society.