${{\mathit \Sigma}}$ 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 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 $\mathit J = 1/2$.
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${{\mathit \Sigma}^{0}}$ 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 ($7.3^{+0.8}_{-0.7}$) $ \times 10^{-20}$ s 
 
$\vert \mu\mathrm {({{\mathit \Sigma}^{0}} \rightarrow {{\mathit \Lambda}})}\vert $ TRANSITION MAGNETIC MOMENT $1.61$ $\pm0.08$ $\mu _{\mathit N}$ 
 
▸  ${{\mathit \Sigma}^{0}}$ DECAY PARAMETERS
Mode  
Fraction ($\Gamma_i$ / $\Gamma$) Scale Factor/
Conf. Level		 P(MeV/c)  
$\Gamma_{1}$ ${{\mathit \Lambda}}{{\mathit \gamma}}$ $\sim100$ $\%$ 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
 
[1] A theoretical value using QED.