${{\mathit \Xi}}$ BARYONS
($\mathit S$ = $-2$, $\mathit I$ = 1/2)
${{\mathit \Xi}^{0}}$ = ${\mathit {\mathit u}}$ ${\mathit {\mathit s}}$ ${\mathit {\mathit s}}$, ${{\mathit \Xi}^{-}}$ = ${\mathit {\mathit d}}$ ${\mathit {\mathit s}}$ ${\mathit {\mathit s}}$

${{\mathit \Xi}^{-}}$

$I(J^P)$ = $1/2(1/2^{+})$ 
The parity has not actually been measured, but ${}^{}{}^{+}$ is of course expected. We have omitted some results that have been superseded by later experiments. See our earlier editions.
${{\mathit \Xi}^{-}}$ MASS   $1321.71 \pm0.07$ MeV 
${{\overline{\mathit \Xi}}^{+}}$ MASS   $1321.71 \pm0.07$ MeV 
(${\mathit m}_{{{\mathit \Xi}^{-}}}–{\mathit m}_{{{\overline{\mathit \Xi}}^{+}}}$) $/$ ${\mathit m}_{{{\mathit \Xi}^{-}}}$   $(-3 \pm9) \times 10^{-5}$  
${{\mathit \Xi}^{-}}$ MEAN LIFE   $(1.639 \pm0.015) \times 10^{-10}$ s 
${{\overline{\mathit \Xi}}^{+}}$ MEAN LIFE   $(1.70 \pm0.14) \times 10^{-10}$ s 
(${\mathit \tau}_{{{\mathit \Xi}^{-}}}–{\mathit \tau}_{{{\overline{\mathit \Xi}}^{+}}}$) $/$ ${\mathit \tau}_{{{\mathit \Xi}^{-}}}$   $-0.01 \pm0.07$  
${{\mathit \Xi}^{-}}$ MAGNETIC MOMENT   $-0.6507 \pm0.0025$ $\mu _{\mathit N}$ 
${{\overline{\mathit \Xi}}^{+}}$ MAGNETIC MOMENT   $0.657 \pm0.034$ $\mu _{\mathit N}$ 
(${\mathit \mu}_{{{\mathit \Xi}^{-}}}$ + ${\mathit \mu}_{{{\overline{\mathit \Xi}}^{+}}}$) $/$ $\vert {\mathit \mu}_{{{\mathit \Xi}^{-}}}\vert $   $+0.01 \pm0.05$  
${{\mathit \Xi}}$ DECAY PARAMETERS
$\alpha\mathrm {({{\mathit \Xi}^{-}})}{}\alpha _{−}({{\mathit \Lambda}}$)   $-0.291 \pm0.004$  (S = 1.8)
$\alpha ({{\mathit \Xi}^{-}}$) for ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$   $-0.390 \pm0.007$  (S = 2.0)
$\alpha ({{\overline{\mathit \Xi}}^{+}}$) for ${{\overline{\mathit \Xi}}^{+}}$ $\rightarrow$ ${{\overline{\mathit \Lambda}}}{{\mathit \pi}^{+}}$   $0.371 \pm0.007$  
($\alpha $ + ${{\overline{\mathit \alpha}}}$) $/$ ($\alpha $ $−$ ${{\overline{\mathit \alpha}}}$) for ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$, ${{\overline{\mathit \Xi}}^{+}}$ $\rightarrow$ ${{\overline{\mathit \Lambda}}}{{\mathit \pi}^{+}}$   $0.006 \pm0.014$  
${[\alpha\mathrm {({{\mathit \Xi}^{-}})}\alpha_-({{\mathit \Lambda}}) − \alpha\mathrm {({{\overline{\mathit \Xi}}^{+}})}\alpha_+({{\overline{\mathit \Lambda}}})]\over [\alpha\mathrm {({{\mathit \Xi}^{-}})}\alpha_-({{\mathit \Lambda}}) + \alpha\mathrm {({{\overline{\mathit \Xi}}^{+}})}\alpha_+({{\overline{\mathit \Lambda}}})]}$   $0.0000 \pm0.0007$  
$\phi $ ANGLE FOR ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$ (tan$\phi $ = $\beta /\gamma $)   $-1.2 \pm1.0$ $^\circ{}$ (S = 1.4)
$\phi $ ANGLE FOR ${{\overline{\mathit \Xi}}^{+}}$ $\rightarrow$ ${{\overline{\mathit \Lambda}}}{{\mathit \pi}^{+}}$ (tan$\phi $ = $\beta /\gamma $)   $-1.2 \pm1.2$ $^\circ{}$ 
$\Delta \Phi _{CP}$ = ($\Phi _{-}$+ $\Phi _{+}$)/2   $-0.3 \pm0.8$ $^\circ{}$ 
${\mathit g}_{{{\mathit A}}}$ $/$ ${\mathit g}_{{{\mathit V}}}$ FOR ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$   $-0.25 \pm0.05$  
$\Gamma_{1}$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$   $(99.887\pm{0.035})\%$ 140
$\Gamma_{2}$ ${{\mathit \Sigma}^{-}}{{\mathit \gamma}}$   $(1.27\pm{0.23})\times 10^{-4}$ 118
$\Gamma_{3}$ ${{\mathit \Lambda}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$   $(5.63\pm{0.31})\times 10^{-4}$ 190
$\Gamma_{4}$ ${{\mathit \Lambda}}{{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}$   $(3.5^{+3.5}_{-2.2})\times 10^{-4}$ 163
$\Gamma_{5}$ ${{\mathit \Sigma}^{0}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$   $(8.7\pm{1.7})\times 10^{-5}$ 123
$\Gamma_{6}$ ${{\mathit \Sigma}^{0}}{{\mathit \mu}^{-}}{{\overline{\mathit \nu}}_{{{\mu}}}}$   $<8\times 10^{-4}$ CL=90% 70
$\Gamma_{7}$ ${{\mathit \Xi}^{0}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{{e}}}}$   $<2.59\times 10^{-4}$ CL=90% 7
Constrained Fit information