hep-ph/9211223
On the Limits of Chiral Perturbation Theory
Thomas Appelquist and John Terning
13 pages, Latex, YCTP-P41-92; we have clarified some of the discussions, the conclusions are unchanged.
Journal-ref: Phys. Rev. D47 (1993) 3075-3078
We consider the relation between the breakdown scale of chiral perturbation theory, $\Lambda_\chi$, for large values of $N$ (flavor), and the scale associated with ``new" physical thresholds. This question is addressed using both the linear $\sigma$ model and an asymptotically-free gauge theory to describe the high energy dynamics. It is suggested that the massive physical threshold could be well above $\Lambda_\chi$.