Cross Sections and Transverse Single-Spin Asymmetries in Forward Neutral-Pion Production from Proton Collisions at \sqrt{s} = 200 GeV

Abstract

Measurements of the production of forward high-energy pi0 mesons from transversely polarized proton collisions at \sqrt{s}=200 GeV are reported. The cross section is generally consistent with next-to-leading order perturbative QCD calculations. The analyzing power is small at x_F below about 0.3, and becomes positive and large at higher x_F, similar to the trend in data at \sqrt{s}<=20 GeV. The analyzing power is in qualitative agreement with perturbative QCD model expectations. This is the first significant spin result seen for particles produced with p_T>1 GeV/c at a polarized proton collider.

6 pages, 3 figures. v2 with minor formatting and text changes as requested by Phys. Rev. Lett. Plain text table of data in these figures and other STAR publications may be found at http://www.star.bnl.gov/central/publications/

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