Herman Feshbach Prize in Theoretical Nuclear Physics (2022): The curious physics behind the breakdown of an effective field theory.

Understanding better the radius of convergence of effective field theory expansions for nuclear physics is important for estimating errors at each order, and for finding ways to extend the range of its applicability. Here I discuss some very curious physics that controls the convergence of the KSW expansion in the triplet channel. High order calculations in a simplified system can reveal the problem in detail and corroborate the semi-analytic theory of Michael Birse for how the expansion breaks down. It is hoped that this result will eventually lead to a method for extending the validity of the expansion to higher energy physics.