G. Guglielmo

Measurement of the Omega - magnetic moment.

A sample of 24 700 {Omega}{sup {minus}} hyperons was produced by a prolarized neutral beam in a spin-transfer reaction. The {Omega}{sup {minus}} polarizations are found to be {minus}0.054{plus minus}0.019 and {minus}0.149{plus minus}0.055 at mean {Omega}{sup {minus}} momenta of 322 and 398 GeV/{ital c}, respectively. The directions of these polarizations give an {Omega}{sup {minus}} magnetic moment of {minus}(1.94{plus minus}0.17{plus minus}0.14){mu}{sub {ital N}}

Search for direct CP violation in nonleptonic decays of charged Xi and lambda hyperons

A search for direct CP violation in the nonleptonic decays of hyperons has been performed. In comparing the product of the decay parameters, alpha(Xi)alpha(Lambda), in terms of an asymmetry parameter, A(XiLambda), between hyperons and antihyperons in the charged Xi-->Lambdapi and Lambda-->ppi decay sequence, we found no evidence of direct CP violation. The parameter A(XiLambda) was measured to be 0.012+/-0.014.

Production polarization and magnetic moment of Xi -bar+ antihyperons produced by 800-GeV/c protons.

The polarization of {bar {Xi}}{sup +} hyperons produced by 800-GeV/{ital c} protons in the inclusive reaction {ital p}+Be{r arrow}{bar {Xi}}{sup +}+{ital X} has been measured. The average polarization of the {bar {Xi}}{sup +}, at a mean {ital x}{sub {ital F}}=0.39 and {ital p}{sub {ital t}}=0.76 GeV/{ital c}, is {minus}0.097{plus minus}0.012{plus minus}0.009. The magnetic moment of the {bar {Xi}}{sup +} is 0.657{plus minus}0.028{plus minus}0.020 nuclear magneton.

Search for direct CP violation in non-leptonic decays of charged Xi and Lambda hyperons

A search for direct CP violation in the nonleptonic decays of hyperons has been performed. In comparing the product of the decay parameters, alpha(Xi)alpha(Lambda), in terms of an asymmetry parameter, A(XiLambda), between hyperons and antihyperons in the charged Xi-->Lambdapi and Lambda-->ppi decay sequence, we found no evidence of direct CP violation. The parameter A(XiLambda) was measured to be 0.012+/-0.014.

Measurement of decay parameters for Xi- --> Lambda pi- decay.

Based on 1.35 x 10(6) polarized Xi(-) events, we measure the parameter phi(Xi) to be -1.61 degrees +/-2.66 degrees +/-0.37 degrees for the Xi(-)-->Lambda pi(-) decay. New results for the parameters beta(Xi) and gamma(Xi) are also presented. Assuming that the CP-violating phase difference is negligible, we deduce the strong phase difference between the P-wave and S-wave amplitudes of the Lambda pi final state to be 3.17 degrees +/-5.28 degrees +/-0.73 degrees, reducing the uncertainty in estimating the level of CP violation in Xi-hyperon decay.

Precise measurement of the magnetic moment

With 4.36{times}10{sup 6} events, spin precession in a magnetic field has been used to measure the magnetic moment of the {Xi}{sup {minus}} hyperon as {minus}0.6505{plus minus}0.0025 nuclear magnetons.

Measurement of decay parameters for Ξ- → Λπ- decay

Based on 1.35 x 10(6) polarized Xi(-) events, we measure the parameter phi(Xi) to be -1.61 degrees +/-2.66 degrees +/-0.37 degrees for the Xi(-)-->Lambda pi(-) decay. New results for the parameters beta(Xi) and gamma(Xi) are also presented. Assuming that the CP-violating phase difference is negligible, we deduce the strong phase difference between the P-wave and S-wave amplitudes of the Lambda pi final state to be 3.17 degrees +/-5.28 degrees +/-0.73 degrees, reducing the uncertainty in estimating the level of CP violation in Xi-hyperon decay.

Precise measurement of the Xi - magnetic moment.

With 4.36{times}10{sup 6} events, spin precession in a magnetic field has been used to measure the magnetic moment of the {Xi}{sup {minus}} hyperon as {minus}0.6505{plus minus}0.0025 nuclear magnetons.

Preliminary results from E756 on the Ξ− and Ω− magnetic moments

We have used the spin precession technique to measure the Ξ− and Ω− magnetic moments. The preliminary results are μ(Ξ−)=−0.64±0.02 nuclear magnetons and μ(Ω−)=−2.0±0.2 nuclear magnetons where the error for both measurements is statistical. The polarization of Ξ−’s produced at 2.5 mr by 800 GeV protons on a Be target was 11% while the polarization of Ω−’s was consistent with zero. Polarized Ξ−’s and Ω−’s were produced using spin transfer from a polarized neutral hyperon beam. The Ω− polarization at 325 GeV/c was 6.5%.

Polarization and spin transfer of Ω− and Ξ− hyperons at 800 GeV

Fermilab experiment E756 has measured the polarization of W− hyperons produced by 800 GeV protons to be small compared to that of Ξ− hyperons. When produced by a neutral beam containing polarized Λ and Ξ0 hyperons, both the Ω− and the Ξ− have a significant polarization indicating a large spin transfer at high energies.