Determination of the $Lambda_c^+$ spin via the reaction $e^+e^-toLambda_c^+barLambda_c^-$

We report on a comparison of two possible $Lambda_c^+$ spin hypotheses, $J=frac{1}{2}$ and $frac{3}{2}$, via the process $e^+e^-toLambda_c^+barLambda_c^-$, using the angular distributions of $Lambda_c^+$ decays into $pK_S^0$, $Lambdapi^+$, $Sigma^0pi^+$, and $Sigma^+pi^0$. The data were recorded at $sqrt s = 4.6$ GeV with the BESIII detector and correspond to an integrated luminosity of 587 pb$^{-1}$. The $Lambda_c^+$ 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.