Speaker
Description
We consider three-particle systems consisting of two identical particles and a third that is different, with all being spinless, e.g. $\pi^+ \pi^+ K^+$. We generalize the formalism necessary to extract two- and three-particle infinite-volume scattering amplitudes from the spectrum of such systems in finite volume. We use a relativistic formalism based on an all-orders diagrammatic analysis in generic effective field theory, adopting the methodology used recently to study the case of three nondegenerate particles. We present both a direct derivation, and also a cross-check based on an appropriate limit and projection of the fully nondegenerate formalism. Lastly, we work out the threshold expansions for the three-particle K-matrix that will be needed in practical applications, both for systems with two identical particles plus a third, and also for the fully nondegenerate theory.
