Using $4.5{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data samples collected at center-of-mass energies ranging from 4.600 to 4.698 GeV with the BESIII detector at the BEPCII collider, we measured the absolute branching fraction for the inclusive semileptonic decay ${\mathrm{\Lambda }}_c^{+}\to X{e}^{+}{\nu }_e$, where $X$ refers to any possible particle system. The branching fraction of the decay is determined to be $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to X{e}^{+}{\nu }_e)=(4.06\pm 0.10_{\mathrm{stat}}\pm 0.09_{\mathrm{syst}})\%$. Our result improves the precision of previous measurements of $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to X{e}^{+}{\nu }_e)$ by more than threefold. Using the known ${\mathrm{\Lambda }}_c^{+}$ lifetime and the charge-averaged semileptonic decay width of nonstrange charmed mesons, we measure the ratio of inclusive semileptonic decay widths $\mathrm{\Gamma }({\mathrm{\Lambda }}_c^{+}\to X{e}^{+}{\nu }_e)/\overline{\mathrm{\Gamma }}(D\to X{e}^{+}{\nu }_e)=1.28\pm 0.05$, where statistical and systematic uncertainties are combined.

• Received 7 December 2022
• Accepted 27 February 2023

DOI:https://doi.org/10.1103/PhysRevD.107.052005

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Published by the American Physical Society