Measurement of the magnetic moment and of the decay parameters of theΞ−hyperon

A measurement of the magnetic moment and of the decay parameters of the ${\Xi }^{-}$ hyperon is reported. The measurement gave ${\mu }_{\Xi }=(-2.1\mathrm{}\pm 0.8)$ nuclear magnetons, corresponding to a gyromagnetic ratio of $g_{\Xi }=4.2\mathrm{}\pm 1.6$. The measured ${\Xi }^{-}$ decay parameters are ${\alpha }_{\Xi }=-0.39\mathrm{}\pm 0.05$, ${\beta }_{\Xi }=0.08\mathrm{}\pm 0.26$, ${\gamma }_{\Xi }=0.92\mathrm{}\pm 0.03$ (${\phi }_{\Xi }=5\mathrm{}°\pm 16°$); and the lifetime ${\tau }_{\Xi }=(1.637\mathrm{}\pm 0.050)\times {10}^{-10\mathrm{}}$ sec. In the accepted angular range for the production of the ${\Xi }^{-}$ (about $4.2°<{\theta }_{\mathrm{lab}}<11.5\mathrm{}°$) in the reaction $K^{-}+p\to K^{+}+{\Xi }^{-}$, the polarization of the ${\Xi }^{-}$ is 0.29 ± 0.10, 0.44 ± 0.09, 0.36 ± 0.10, and 0.21 ± 0.06 at laboratory momenta of 1.74, 1.80, 1.87, and 1.83 GeV/c, respectively.