Physical Review Letters 97,25 (2006)
We present measurements of the inclusive branching fractions for the decays D+-> Xe+nu(e) and D-0 -> Xe+nu(e), using 281 pb(-1) of data collected on the psi(3770) resonance with the CLEO-c detector. We find B(D-0 -> Xe+nu(e))=(6.46 +/- 0.17 +/- 0.13)% and B(D+-> Xe+nu(e))=(16.13 +/- 0.20 +/- 0.33)%. Using the known D meson lifetimes, we obtain the ratio Gamma(+sl)(D)/Gamma(0sl)(D)=0.985 +/- 0.028 +/- 0.015, confirming isospin invariance at the level of 3%. The positron momentum spectra from D+ and D-0 have consistent shapes.
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