${{\mathit \Sigma}}$ 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:
S019

${{\mathit \Sigma}^{+}}$

$I(J^P)$ = $1(1/2^{+})$ 
We have omitted some results that have been superseded by later experiments. See our earlier editions.
${{\mathit \Sigma}^{+}}$ MASS   $1189.37 \pm0.07$ MeV (S = 2.2)
 
${{\mathit \Sigma}^{+}}$ MEAN LIFE   $(8.018 \pm0.026) \times 10^{-11}$ s 
 
(${\mathit \tau}_{{{\mathit \Sigma}^{+}}}–{\mathit \tau}_{{{\overline{\mathit \Sigma}}^{-}}}$) $/$ ${\mathit \tau}_{{{\mathit \Sigma}^{+}}}$   $-0.0006 \pm0.0012$  
 
${{\mathit \Sigma}^{+}}$ MAGNETIC MOMENT   $2.458 \pm0.010$ $\mu _{\mathit N}$ (S = 2.1)
 
(${\mathit \mu}_{{{\mathit \Sigma}^{+}}}$ $+$ ${\mathit \mu}_{{{\overline{\mathit \Sigma}}^{-}}}$) $/$ ${\mathit \mu}_{{{\mathit \Sigma}^{+}}}$   $0.014 \pm0.015$  
 
${{\mathit \Sigma}^{+}}$ DECAY PARAMETERS
$\alpha _{0}$ FOR ${{\mathit \Sigma}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{0}}$   $-0.982 \pm0.014$  
 
${{\overline{\mathit \alpha}}_{{{0}}}}$ FOR ${{\overline{\mathit \Sigma}}^{-}}$ $\rightarrow$ ${{\overline{\mathit p}}}{{\mathit \pi}^{0}}$   $0.99 \pm0.04$  
 
(${{\mathit \alpha}_{{{0}}}}$ + ${{\overline{\mathit \alpha}}_{{{0}}}}$) $/$ (${{\mathit \alpha}_{{{0}}}}$ $−$ ${{\overline{\mathit \alpha}}_{{{0}}}}$)   $0.00 \pm0.04$  
 
$\phi _{0}$ ANGLE FOR ${{\mathit \Sigma}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \pi}^{0}}$ ($\phi _{0}$ = $\beta /\gamma $)   $36 \pm34$ $^\circ{}$ 
 
$\alpha _{+}$ $/$ $\alpha _{0}$   $-0.0498 \pm0.0027$  
 
$\alpha _{+}$ FOR ${{\mathit \Sigma}^{+}}$ $\rightarrow$ ${{\mathit n}}{{\mathit \pi}^{+}}$   $0.0489 \pm0.0026$  
 
$\phi _{+}$ ANGLE FOR ${{\mathit \Sigma}^{+}}$ $\rightarrow$ ${{\mathit n}}{{\mathit \pi}^{+}}$ ($\phi _{+}$ = $\beta /\gamma $)   $167 \pm20$ $^\circ{}$ (S = 1.1)
 
${{\overline{\mathit \alpha}}_{{{-}}}}$ FOR ${{\overline{\mathit \Sigma}}^{-}}$ $\rightarrow$ ${{\overline{\mathit n}}}{{\mathit \pi}^{-}}$   $-0.057 \pm0.005$  
 
${{\overline{\mathit \alpha}}_{{{-}}}}$ $/$ ${{\overline{\mathit \alpha}}_{{{0}}}}$   $-0.057 \pm0.006$  
 
(${{\mathit \alpha}_{{{+}}}}$ + ${{\overline{\mathit \alpha}}_{{{-}}}}$) $/$ (${{\mathit \alpha}_{{{+}}}}$ $−$ ${{\overline{\mathit \alpha}}_{{{-}}}}$)   $-0.08 \pm0.06$  
 
$\alpha _{\gamma }$ FOR ${{\mathit \Sigma}^{+}}$ $\rightarrow$ ${{\mathit p}}{{\mathit \gamma}}$   $-0.69 \pm0.05$  
 
$\Gamma_{1}$ ${{\mathit p}}{{\mathit \pi}^{0}}$   $(51.47\pm{0.30})\%$ 189
 
$\Gamma_{2}$ ${{\mathit n}}{{\mathit \pi}^{+}}$   $(48.43\pm{0.30})\%$ 185
 
$\Gamma_{3}$ ${{\mathit p}}{{\mathit \gamma}}$   $(1.04\pm{0.06})\times 10^{-3}$ S=2.4  225
 
$\Gamma_{4}$ ${{\mathit n}}{{\mathit \pi}^{+}}{{\mathit \gamma}}$  [1] $(4.5\pm{0.5})\times 10^{-4}$ 185
 
$\Gamma_{5}$ ${{\mathit \Lambda}}{{\mathit e}^{+}}{{\mathit \nu}_{{{e}}}}$   $(2.3\pm{0.4})\times 10^{-5}$ 71
 
FOOTNOTES
Constrained Fit information