Analyzing power in inclusive π+, π−, and Λ production at high xF with 200 GeV polarized protons

Abstract

The analyzing power in inclusive charged pion production has been measured using the 200 GeV Fermilab polarized proton beam. A striking dependence in xF is observed in which AN increases from 0 to 0.42 with increasing xF for the π+ data and decreases from 0 to −0.38 with increasing xF for π− data. The kinematic range covered is 0.2≤xF≤0.9 and 0.2≤pT≤2.0 GeV/c. The analyzing power for inclusive Λ production has also been measured and is consistent with zero. In a simple model, our data indicate that at large xF the transverse spin of the proton is correlated with that of its quark constituents.