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

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

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 We have omitted some results that have been superseded by later experiments.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 $   $+0.01 \pm0.05$  
${{\boldsymbol \Xi}^{-}}$ DECAY PARAMETERS
$\alpha\mathrm {({{\mathit \Xi}^{-}})}{}\alpha _{−}({{\mathit \Lambda}}$)   $-0.294 \pm0.005$  (S = 1.7)
$\alpha $ FOR ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$   $-0.458 \pm0.012$  (S = 1.8)
${[\alpha\mathrm {({{\mathit \Xi}^{-}})}\alpha_-({{\mathit \Lambda}}) − \alpha\mathrm {({{\overline{\mathit \Xi}}^{+}})}\alpha_+({{\overline{\mathit \Lambda}}})]\over [\alpha\mathrm {({{\mathit \Xi}^{-}})}\alpha_-({{\mathit \Lambda}}) + \alpha\mathrm {({{\overline{\mathit \Xi}}^{+}})}\alpha_+({{\overline{\mathit \Lambda}}})]}$   $0.0000 \pm0.0007$  
$\phi $ ANGLE FOR ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$ (tan$\phi $ = $\beta /\gamma $)   $-2.1 \pm0.8$ $^\circ{}$ 
${\mathit g}_{{{\mathit A}}}$ $/$ ${\mathit g}_{{{\mathit V}}}$ 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
$\Gamma_{7}$ ${{\mathit \Xi}^{0}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{e}}}$ $<2.3\times 10^{-3}$CL=90%7
    constrained fit information