Improved measurement of the absolute branching fraction of inclusive semileptonic ${\mathrm{\Lambda }}_c^{+}$ decay

Using $4.5{\mathrm{f}\mathrm{b}}^{-1}$ 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 $\mathcal{B}({\Lambda }_c^{+}\to X{e}^{+}{\nu }_e)=(4.06\pm {0.10}_{\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}\mathrm{.}}\pm {0.09}_{\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}\mathrm{.}})\mathrm{\%}$. Our result improves the precision of previous measurement of $\mathcal{B}({\Lambda }_c^{+}\to X{e}^{+}{\nu }_e)$ 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 $\mathrm{\Gamma }({\mathrm{\Lambda }}_c^{+}\to X{e}^{+}{\nu }_e)\mathrm{/}\bar{\mathrm{\Gamma }}(D\to X{e}^{+}{\nu }_e)=1.28\pm 0.05$, where statistical and systematic uncertainties are combined.