Rescattering effects in proton elastic scattering from halo nuclei: A test of the Glauber approximation

Faddeev multiple scattering calculations are performed for p-¹¹Be at 100, 150, 200 MeV incident energies, and compared with full calculations where the series is calculated using Pad\'e summation. We show that single scattering approximation overestimates the cross section at small angles, and that higher order effects are important at these intermediate energies. One needs to go beyond double scattering and include third order terms that are absent in Glauber multiple scattering formulations. This is evidence of the breakdown of the Glauber scattering framework at these energies. We also show that rescattering within the halo nucleus gives the dominant contribution to these third order terms. We point out that it is crucial to use a realistic NN interaction in any meaningful scattering calculation, particularly at these energies.