Calculation of the axial charge in the ε and ε′ regimes of heavy-baryon chiral perturbation theory

The axial charge g(A) is calculated in the epsilon regime of heavy-baryon chiral perturbation theory to order epsilon(3). To perform this calculation, we develop a technique to compute baryon properties in the epsilon regime of chiral perturbation theory. This technique includes contributions from pion zero momentum modes and can be used at arbitrary order, diagram by diagram, in the epsilon regime to calculate any matrix element. Also, a calculation of g(A) in the epsilon' regime to order epsilon'(3) is performed. A discussion of the domain of applicability for both the epsilon and epsilon' regimes is also included.