Measurement of Transverse Single Spin Asymmetry A_N in Eta Mass Region at Large Feynman X_F with the STAR Forward Pion Detector

Understand

The large values of the transverse single spin asymmetry, A_N, seen in forward pi0 production from polarized proton collisions have stimulated important questions and have been studied in QCD based transverse spin models.

• We report the first RHIC measurement of A_N for the two photon mass region of the eta meson.
• The eta peak for meson energies greater than 50 GeV (Feynman x_F >0.5) was observed in the STAR Forward Pion Detectors, along with pi0 mesons, at pseudo-rapidity of 3.65 in sqrt{s}=200 GeV pp collisions.
• The pi0 transverse asymmetry, which has already been reported in detail by the STAR collaboration, is compared to the transverse asymmetry in the eta mass region.