${{\boldsymbol \Sigma}}$ BARYONS
($\boldsymbol S$ = $-1$, $\boldsymbol I$ = 1)
${{\mathit \Sigma}^{+}}$ = ${\mathit {\mathit u}}$ ${\mathit {\mathit u}}$ ${\mathit {\mathit s}}$, ${{\mathit \Sigma}^{0}}$ = ${\mathit {\mathit u}}$ ${\mathit {\mathit d}}$ ${\mathit {\mathit s}}$, ${{\mathit \Sigma}^{-}}$ = ${\mathit {\mathit d}}$ ${\mathit {\mathit d}}$ ${\mathit {\mathit s}}$
INSPIRE search

${{\boldsymbol \Sigma}^{0}}$ $I(J^P)$ = $1(1/2^{+})$

COURANT 1963 and ALFF 1965 , using ${{\mathit \Sigma}^{0}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ decays (Dalitz decays), determined the ${{\mathit \Sigma}^{0}}$ parity to be positive, given that $\mathit J = 1/2$ and that certain very reasonable assumptions about form factors are true. The results of experiments involving the Primakoff effect, from which the ${{\mathit \Sigma}^{0}}$ mean life and ${{\mathit \Sigma}^{0}}$ $\rightarrow$ ${{\mathit \Lambda}}$ transition magnetic moment come (see below), strongly support $\mathit J = 1/2$.
${{\mathit \Sigma}^{0}}$ MASS   $1192.642 \pm0.024$ MeV 
${\mathit m}_{{{\mathit \Sigma}^{-}}}–{\mathit m}_{{{\mathit \Sigma}^{0}}}$   $4.807 \pm0.035$ MeV (S = 1.1)
${\mathit m}_{{{\mathit \Sigma}^{0}}}–{\mathit m}_{{{\mathit \Lambda}}}$   $76.959 \pm0.023$ MeV 
${{\mathit \Sigma}^{0}}$ MEAN LIFE   $(74 \pm7) \times 10^{-21}$ s 
$\vert \mu\mathrm {( {{\mathit \Sigma}^{0}} \rightarrow {{\mathit \Lambda}} )}\vert $ TRANSITION MAGNETIC MOMENT   $1.61 \pm0.08$ $\mu _{\mathit N}$ 
$\Gamma_{1}$ ${{\mathit \Lambda}}{{\mathit \gamma}}$ $(100)\%$74
$\Gamma_{2}$ ${{\mathit \Lambda}}{{\mathit \gamma}}{{\mathit \gamma}}$ $<3\%$CL=90%74
$\Gamma_{3}$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit e}^{-}}$ [1]$(5)\times 10^{-3}$74