Recent PHENIX Results on pi+, pi-, and eta Production in polarized pp   Collisions at RHIC at sqrt(s) = 200 GeV
  Measurements of double helicity asymmetries for inclusive hadron production in polarized proton-proton collisions are sensitive to spin-dependent parton distribution functions, in particular to the gluon distribution function. This study focuses on double helicity asymmetries in eta and charged pion production at mid-rapidity, as well as on the eta cross section and fragmentation functions. 
Frank Ellinghaus (for the PHENIX Collaboration)