Transverse single-spin asymmetry and cross section for π0 and η mesons at large Feynman x in p →+p collisions at √s=200GeV

Abstract

Measurements of the differential cross section and the transverse single-spin asymmetry, A N, vs x F for π0 and η mesons are reported for 0.4 <0.75 at an average pseudorapidity of 3.68. A data sample of approximately 6.3pb -1 was analyzed, which was recorded during p →+p collisions at √s=200GeV by the STAR experiment at RHIC. The average transverse beam polarization was 56%. The cross section for π0, including the previously unmeasured region of x F>0.55, is consistent with a perturbative QCD prediction, and the η/π0 cross-section ratio agrees with existing midrapidity measurements. For 0.55 <0.75, the average A N for η is 0.210±0.056, and that for π0 is 0.081±0.016. The probability that these two asymmetries are equal is ∼3%. © 2012 American Physical Society.