Constraining 1+J -> 2 Coupled-Channel Amplitudes In A Finite Volume

Whether one is interested in accessing the excited spectrum of hadrons or testing the standard model of particle physics, electroweak transition processes involving multihadron channels in the final state play an important role in a variety of experiments. Presently the primary theoretical tool with which one can study such reactions is lattice QCD, which is defined in a finite spacetime volume. In this work, we investigate the feasibility of implementing existing finite-volume formalism in realistic lattice QCD calculation of reactions in which a stable hadron can transition to one of several two-hadron channels under the action of an external current. We provide a conceptual description of the coupled-channel transition formalism, a practical road map for carrying out a calculation, and an illustration of the approach using synthetic data for two nontrivial resonant toy models. The results provide a proof of principle that such reactions can indeed be constrained using modern-day lattice QCD calculations, motivating explicit computation in the near future.