Measurement of the absolute branching fraction of the inclusive semileptonic $\Lambda_c^+$ decay

Abstract

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 $\sqrt{s}$ = 4.6 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 $\mathcal{B}(\Lambda_c^+ \rightarrow X e^+ \nu_e) = (3.95\pm0.34\pm0.09)\%$, 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 $\Gamma(\Lambda_c^+ \rightarrow X e^+ \nu_e)/\bar{\Gamma}(D\rightarrow X e^+ \nu_e)= 1.26\pm0.12$.