Polarization and magnetic moment of theΣ−hyperon

We have measured the magnetic moment of the ${\Sigma }^{-}$ hyperon to be $\mu \left({\Sigma }^{-}\right)=-0.89\mathrm{}\pm 0.14$ nuclear magnetons. The magnitude of the polarization of ${\Sigma }^{-}$ produced at 7.5 mrad by 400-GeV protons in the process $p+\mathrm{Be}\to {\Sigma }^{-}+X$ averages (15.5±3.6)% over the momentum range 120 to 290 GeV/c. The mean ${\Sigma }^{-}$ transverse momentum was 1.32 GeV/c. The polarization direction at production is the same as ${\Sigma }^{+}$ and opposite that of $\Lambda$ and ${\Xi }^0$.