Nonanalyticity in the chiral perturbation theory

Nonanalytic behavior in chiral perturbation theory is studied in the framework of quantum field theory. It is shown that to first order of pion interactions, renormalization does not change nonanalyticity of S-matrix elements. But there is a change in such behavior for current-matrix elements. It is also noted that there are no terms of O(μ²lnμ²) in hadronic masses, pseudoscalar-meson-baryon couplings, and meson-meson scattering amplitudes.