Perturbative EFT calculation of the deuteron longitudinal response function

In this work, we study the longitudinal response function of the deuteron up to next-to-next-to-leading order in chiral effective field theory (Chiral EFT). We use an approach that maintains exact renormalization group (RG) invariance at each order of the EFT expansion by treating all subleading corrections in perturbation theory. To that end, we extent the Lorentz Integral Transform (LIT) method to allow for such a perturbative treatment. In doing so, we further develop the existing work on strictly RG invariant Chiral EFT, which has so far focused primarily on binding energies and static properties, to inelastic processes. We carefully analyze the convergence properties of the theory and find good agreement with available experimental data. Our findings provide the foundation for similar studies of inelastic processes in a range of nuclei, based on perturbatively renormalized EFT schemes.