Measurement of the Absolute Branching Fraction of the Inclusive Semileptonic ${\Lambda }_{c}^{+}$ Decay

Using a data sample of ${e}^{+}{e}^{-}$ collisions corresponding to an integrated luminosity of $567\text{}\text{}{\mathrm{pb}}^{-1}$ collected at a center-of-mass energy of $\sqrt{s}=4.6\text{}\text{}\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fraction of the inclusive semileptonic ${\Lambda }_{c}^{+}$ decay with a double-tag method. We obtain $B\left({\Lambda }_{c}^{+}\to X{e}^{+}{\nu }_{e}\right)=\phantom{\rule{0ex}{0ex}}\left(3.95±0.34±0.09\right)%$, where the first uncertainty is statistical and the second systematic. Using the known ${\Lambda }_{c}^{+}$ lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons (${D}^{0}$ and ${D}^{+}$), we obtain the ratio of the inclusive semileptonic decay widths $\Gamma \left({\Lambda }_{c}^{+}\to X{e}^{+}{\nu }_{e}\right)/\phantom{\rule{0ex}{0ex}}\overline{\Gamma }\left(D\to X{e}^{+}{\nu }_{e}\right)=1.26±0.12$.