Physical Review D 81,5 (2010)
We have measured the inclusive semileptonic branching fractions of D-0, D+, and D-s(+) mesons. For these measurements, we have used the full CLEO-c open-charm data samples, 818 pb(-1) at E-CM = 3.774 GeV, giving D-0(D) over bar (0) and D+D- events, and 602 pb(-1) at E-CM = 4.170 GeV, giving D-s*D-+/-(s)-/+ events. We obtain B(D-0 -> Xe+nu(e)) = (6.46 +/- 0.09 +/- 0.11)%, B(D+ -> Xe+nu(e)) = (16.13 +/- 0.10 +/- 0.29)%, and B(D-s(+) -> Xe+nu(e)) = (6.52 +/- 0.39 +/- 0.15)%, where the first uncertainties are statistical and the second are systematic. From these and lifetimes obtained elsewhere, we obtain the ratios of semileptonic decay widths Gamma(D+ -> Xe+nu(e))/Gamma(D-0 -> Xe+nu(e)) = 0.985 +/- 0.015 +/- 0.024 and Gamma(D-s(+) -> Xe+nu(e))/Gamma(D-0 -> Xe+nu(e)) = 0.828 +/- 0.051 +/- 0.025. The ratio of D+ and D-0 is consistent with the isospin symmetry prediction of unity, and the ratio of D-s(+) and D-0 differs from unity, as expected.
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