Heavy-baryon chiral perturbation theory and reparametrization invariance
  We examine the constraints imposed by reparametrization invariance on heavy-baryon chiral perturbation theory (HBChPT). We study the case of 3 flavors and consider both the strong and weak ($|\Delta S| =1$) interaction sector. Some of the parameters in the HBChPT Lagrangian are fixed as a consequence of reparametrization invariance. We discuss the consequences for the calculation of hyperon weak radiative decays in HBChPT. 
J. W. Bos, D. Chang, S. C. Lee, Y. C. Lin, and H. H. Shih