Measurement ofD0lifetime ine+e−annihilation at high energy

A measurement of the D/sup 0/ lifetime using the impact-parameter method is presented. The D/sup 0/ sample is obtained from identified D/sup asteriskplus-or-minus/ decays in e/sup +/e/sup -/ annihilations into hadrons at center-of-mass energy of 29 GeV. The maximum-likelihood method used is found to be insensitive to the specific choice of cuts and uncertainties in backgrounds, giving the D/sup 0/ lifetime of (4.6 +- 1.5 (statistical)/sub -0.5//sup +0.6/(systematic)) x 10/sup -13/ sec. The consistency and bias of the method are checked. Combining the measurement with the semileptonic branching ratio of D/sup 0/, we estimate the semileptonic decay rate of D/sup 0/ to be (1.6 +- 0.6) x 10/sup 11/ sec/sup -1/. The corresponding value of the effective charm-quark mass is found to be consistent with the typical constituent mass of charm quark.