Single-spin asymmetries and invariant cross sections of the high transverse-momentum inclusive pi 0 production in 200 GeV/c pp and p-barp interactions.
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The 0 inclusive and semi-inclusive, single-spin asymmetries have been measured using transversely polarized, 200-GeV/c proton and antiproton beams colliding with an unpolarized hydrogen target. The measured asymmetries are consistent with zero within the experimental uncertainties for the kinematic region -0.15<(formula presented)3 GeV/c were not correct. These data indicate that PQCD expectations seem confirmed and the higher-twist contribution to the single-spin asymmetry in 0 production at xF=0 is not large. Additional evidence for such a conclusion comes from the measurement of a semi-inclusive 0 asymmetry, where associated charged particles are detected opposite to the 0 azimuthal direction. This experiment also provides high-statistics data on the inclusive 0 cross sections for pp and p-p collisions at s19.4 GeV. 1996 The American Physical Society.