Constraint on \Delta g(x) from \pi^0 production at RHIC
  We determine the polarized gluon distribution \Delta g(x) by a global analysis using current DIS and \pi^0 asymmetry data. The \pi^0 data from RHIC-Spin experiments provide a strong constraint on \Delta g(x), so that its uncertainty is reduced. However, a sign problem appears in the analysis using \pi^0 data, which means that positive and negative distributions are allowed for \Delta g(x). These two types of solutions are discussed. 
M. Hirai, S. Kumano, and N. Saito (Asymmetry Analysis Collaboration)