Measurement of the polarization of the Xi0 (anti-Xi0) hyperon beam by the NA48/1 experiment

A total of 368 415 Ξ 0 → Λ π 0 and 31 171 over(Ξ 0, -) → over(Λ, -) π 0 were selected from data recorded in the NA48/1 experiment during 2002 data taking. From this sample, the polarization of Ξ 0 and over(Ξ 0, -) hyperons was measured to be P Ξ0 = - 0.102 ± 0.012 (stat) ± 0.008 (syst) and P over(Ξ0, -) = - 0.01 ± 0.04 (stat) ± 0.008 (syst). The dependence of P Ξ0 on the Ξ 0 transverse momentum with respect to the primary proton beam is also presented. With the same data sample, the ratio of over(Ξ 0, -) and Ξ 0 fluxes in proton collisions at 400 GeV / c on a beryllium target was measured.