Bayesian analysis and analytic continuation of scattering amplitudes from lattice QCD

We present a novel procedure for analyzing the lattice QCD spectrum via the finite-volume formalism to obtain constraints on multihadron scattering amplitudes at both real and complex energies. This approach combines a Bayesian reconstruction of the scattering amplitude on the real axis with Nevanlinna interpolation for analytic continuation to complex-valued energies. The method is nonparametric, inherently accounting for parametrization dependence within the uncertainty. We demonstrate the applicability of this approach using both toy data and real lattice QCD data in resonant systems from the Hadron Spectrum and the Baryon Scattering collaborations.