Toward emulating nuclear reactions using eigenvector continuation.

We construct an efficient emulator for two-body scattering using the generalized Kohn variational principle and trial wave functions derived from eigenvector continuation. Our emulator simultaneously applies an array of Kohn variational principles with different asymptotic boundary conditions, which allows for detection and removal of spurious singularities known as Kohn anomalies. We then perform a Bayesian analysis of elastic scattering of neutrons off $^{40}$Ca and $^{208}$Pb nuclei using realistic optical potentials. The emulator’s high accuracy and computational speed enable rigorous uncertainty quantification for improving optical potentials in the FRIB era.