Uncertainty Quantification for Phenomenological Optical Potentials*

Optical-model potentials (OMPs), which model the interaction between a projectile and a nuclear target, remain an essential reaction theory ingredient. Though several esteemed phenomenological OMPs are available (including the Koning-Delaroche [KD] and Chapel Hill ’89 [CH89] OMPs), none are equipped with well-calibrated uncertainties. Without reliable UQ, experimentalists, reaction theorists, and evaluators have little way of knowing where to trust these models and where the models break down.

To address this gap, we revisited the classical KD and CH89 OMP analyses and identified two important statistical limitations that hampered the original analyses’ efforts at UQ. We then developed a generic OMP-UQ framework and assigned uncertainties to KD and CH89, yielding two new OMP ensembles, KDUQ and CHUQ. Against both the KD/CH89 training data and a large corpus of test data, our UQ versions show improved reliability and interpretability and can be dropped in anywhere KD and CH89 are already

used. To facilitate including OMP uncertainty as a standard practice in the field, we provide digital copies of our potentials and related tools for forward uncertainty propagation.