Using a data sample of e+e- collisions corresponding to an integrated luminosity of 567 pb-1 collected at a center-of-mass energy of s=4.6 GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic Λc+ decay with a double-tag method. We obtain B(Λc+→Xe+νe)=(3.95±0.34±0.09)%, where the first uncertainty is statistical and the second systematic. Using the known Λc+ lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (D0 and D+), we obtain the ratio of the inclusive semileptonic decay widths Γ(Λc+→Xe+νe)/Γ(D→Xe+νe)=1.26±0.12.
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