${{\mathit \Sigma}}$ BARYONS
($\mathit S$ = $-1$, $\mathit I$ = 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   JSON  (beta) PDGID:
S021

${{\mathit \Sigma}^{0}}$

$I(J^P)$ = $1(1/2^{+})$ 
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
 
FOOTNOTES