Measurement of the polarization and magnetic moment of antihyperons produced by 800-GeV/c protons

The polarization of hyperons produced by 800-GeV/c protons in the inclusive reaction p+Be+X has been measured using a sample of 70 000 decays. The average polarization of the , at a mean xF=0.39 and pt=0.76 GeV/c, is -0.0970.0120.009, compared to -0.1020.0120.010 for the -. The large polarization found for the is not expected in any model for polarization of inclusively produced hyperons. The magnetic moment of the was measured to be 0.6570.0280.020 nuclear magnetons (N), compared to (-0.6740.0210.020)N for the -, in good agreement with CPT invariance.