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

Based on an ${e}^{+}{e}^{-}$ collision data sample corresponding to an integrated luminosity of $567\text{}\text{}{\mathrm{pb}}^{-1}$ taken at the 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 decay ${\Lambda }_{c}^{+}\to \Lambda +X$ to be $B\left({\Lambda }_{c}^{+}\to \Lambda +X\right)=\left(38.{2}_{-2.2}^{+2.8}±0.9\right)%$ using the double-tag method, where $X$ refers to any possible final state particles. In addition, we search for direct $CP$ violation in the charge asymmetry of this inclusive decay for the first time, and obtain ${A}_{CP}\equiv \phantom{\rule{0ex}{0ex}}\left[B\left({\Lambda }_{c}^{+}\to \Lambda +X\right)-B\left({\overline{\Lambda }}_{c}^{-}\to \overline{\Lambda }+X\right)\right]/\left[B\left({\Lambda }_{c}^{+}\to \Lambda +X\right)+B\left({\overline{\Lambda }}_{c}^{-}\to \overline{\Lambda }+X\right)\right]=\left(2.{1}_{-6.6}^{+7.0}±1.6\right)%$, a statistically limited result with no evidence of $CP$ violation.