Ladder approximation for spontaneous chiral-symmetry breaking

This paper examines the validity of the ladder approximation in gauge theories such as technicolor theories in which the coupling is a slowly running function of momentum and is large enough to trigger spontaneous chiral-symmetry breaking. We find that the next-higher-order terms beyond the ladder approximation amount to only a 1%--20% correction, depending on the fermion representation. This indicates that the ladder expansion may provide a much better description of chiral-symmetry breaking than previously thought.