Bridging reaction theory and nuclear structure in $\pi^\pm$-${}^{48}$Ca scattering

We extend the pion-nucleus multiple-scattering framework to include detailed second-order rescattering dynamics for nuclei with non-zero isospin. To account for intermediate charge-exchange and nucleon spin-flip effects, we develop a scattering potential that depends on the one- and two-body densities of the target nucleus. We compute one-body densities from coupled-cluster theory and two-body densities within the Hartree-Fock approximation. To estimate theoretical uncertainties, we employ modern nuclear Hamiltonians derived from chiral effective field theory. While the sensitivity to nuclear structure details is mild, second-order corrections are found to be sizeable and essential for accurately reproducing differential cross sections measured in $\pi^\pm$-${}^{48}$Ca elastic scattering within the $\Delta(1232)$-resonance region