Probing gluon polarization with pi0's in longitudinally polarized proton   collisions at the RHIC-PHENIX experiment
  This report presents double helicity asymmetry in inclusive $\pi^0$ production in polarized proton-proton collisions at a center-of-mass energy ($\sqrt{s}$) of 200 GeV. The data were collected with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC) during the 2004 run. The data are compared to a next-to-leading order perturbative quantum chromodynamic (NLO pQCD) calculation. 
Y. Fukao (for the PHENIX collaboration)