Polarization and magnetic moment of theΣ−hyperon

Abstract

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