${{\boldsymbol \Xi}}$ 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 We have omitted some results that have been superseded by later experiments.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 ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit \pi}^{-}}$ $-0.401 \pm0.010$
 ${[\alpha\mathrm {({{\mathit \Xi}^{-}})}\alpha_-({{\mathit \Lambda}}) − \alpha\mathrm {({{\overline{\mathit \Xi}}^{+}})}\alpha_+({{\overline{\mathit \Lambda}}})]\over [\alpha\mathrm {({{\mathit \Xi}^{-}})}\alpha_-({{\mathit \Lambda}}) + \alpha\mathrm {({{\overline{\mathit \Xi}}^{+}})}\alpha_+({{\overline{\mathit \Lambda}}})]}$ $0.0000 \pm0.0007$
 $\phi$ 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 ${{\mathit \Xi}^{-}}$ $\rightarrow$ ${{\mathit \Lambda}}{{\mathit e}^{-}}{{\overline{\mathit \nu}}_{{e}}}$ $-0.25 \pm0.05$
 constrained fit information