Chiral extrapolation of nucleon axial charge g_A in effective field theory

The extrapolation of nucleon axial charge g_A is investigated within the framework of heavy baryon chiral effective field theory. The intermediate octet and decuplet baryons are included in the one loop calculation. Finite range regularization is applied to improve the convergence in the quark-mass expansion. The lattice data from three different groups are used for the extrapolation. At physical pion mass, the extrapolated g_A are all smaller than the experimental value. (authors)