Determination of the $Λ_c^+$ spin via the reaction $e^+e^-\toΛ_c^+\barΛ_c^-$

Abstract

We report on a comparison of two possible $Λ_c^+$ spin hypotheses, $J=\frac{1}{2}$ and $\frac{3}{2}$, via the process $e^+e^-\toΛ_c^+\barΛ_c^-$, using the angular distributions of $Λ_c^+$ decays into $pK_S^0$, $Λπ^+$, $Σ^0π^+$, and $Σ^+π^0$. 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 $Λ_c^+$ 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.