Ab initio computation of the longitudinal response function in $^{40}$Ca

TL;DR

This paper demonstrates an ab initio approach to compute the longitudinal response function in calcium-40, achieving good agreement with experimental data and highlighting the importance of final state interactions for accurate modeling.

Contribution

It introduces a consistent ab initio method combining coupled-cluster and Lorentz integral transform techniques for nuclear response functions.

Findings

Good agreement with experimental data for $R_L$ in $^{40}$Ca

Final state interactions are crucial for accurate results

Validates approach with $^4$He and Coulomb sum rule comparisons

Abstract

We present a consistent \emph{ab initio} computation of the longitudinal response function $R_L$ in $^{40}$Ca using the coupled-cluster and Lorentz integral transform methods starting from chiral nucleon-nucleon and three-nucleon interactions. We validate our approach by comparing our results for $R_L$ in $^4$He and the Coulomb sum rule in $^{40}$Ca against experimental data and other calculations. For $R_L$ in $^{40}$Ca we obtain a very good agreement with experiment in the quasi-elastic peak up to intermediate momentum transfers, and we find that final state interactions are essential for an accurate description of the data. This work presents a milestone towards \emph{ab initio} computations of neutrino-nucleus cross sections relevant for experimental long-baseline neutrino programs.