We report on a comparison of two possible ${\mathrm{\Lambda }}_c^{+}$ spin hypotheses, $J=\frac{1}{2}$ and $\frac{3}{2}$, via the process $e^{+}{e}^{-}\to {\mathrm{\Lambda }}_c^{+}{\overline{\mathrm{\Lambda }}}_c^{-}$, using the angular distributions of ${\mathrm{\Lambda }}_c^{+}$ decays into $p{K}_S^0$, $\mathrm{\Lambda }{\pi }^{+}$, ${\mathrm{\Sigma }}^0{\pi }^{+}$, and ${\mathrm{\Sigma }}^{+}{\pi }^0$. The data were recorded at $\sqrt{s}=4.6\mathrm{GeV}$ with the BESIII detector and correspond to an integrated luminosity of $587{\mathrm{pb}}^{-1}$. The ${\mathrm{\Lambda }}_c^{+}$ spin is determined to be $J=\frac{1}{2}$, with this value favored over the $\frac{3}{2}$ hypothesis with a significance corresponding to more than 6 Gaussian standard deviations.

• Received 31 October 2020
• Revised 16 February 2021
• Accepted 12 April 2021

DOI:https://doi.org/10.1103/PhysRevD.103.L091101

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Published by the American Physical Society