Based on an $e^{+}{e}^{-}$ collision data sample corresponding to an integrated luminosity of $567{\mathrm{pb}}^{-1}$ taken at the center-of-mass energy of $\sqrt{s}=4.6\mathrm{GeV}$ with the BESIII detector, we measure the absolute branching fraction of the inclusive decay ${\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }+X$ to be $\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }+X)=(38.2_{-2.2}^{+2.8}\pm 0.9)\%$ 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 ${\mathcal{A}}_{CP}\equiv [\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }+X)-\mathcal{B}({\overline{\mathrm{\Lambda }}}_c^{-}\to \overline{\mathrm{\Lambda }}+X)]/[\mathcal{B}({\mathrm{\Lambda }}_c^{+}\to \mathrm{\Lambda }+X)+\mathcal{B}({\overline{\mathrm{\Lambda }}}_c^{-}\to \overline{\mathrm{\Lambda }}+X)]=(2.1_{-6.6}^{+7.0}\pm 1.6)\%$, a statistically limited result with no evidence of $CP$ violation.

• Received 31 March 2018
• Revised 11 June 2018

DOI:https://doi.org/10.1103/PhysRevLett.121.062003

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Published by the American Physical Society