The cross section for $p{-}^{11}\mathrm{Li}$ inelastic scattering at 68 MeV/nucleon is evaluated using the multiple scattering expansion of the total transition amplitude (MST) formalism, and compared with the breakup in the shakeoff approximation. Three different potential models for ${}^{11}\mathrm{Li}$ are used to calculate the ${}^{11}\mathrm{Li}{(p,p}^{\prime })$ continuum excitations, and all show peaks below 3 MeV of excitation energy, both in resonant and some nonresonant channels. In the most realistic model of ${}^{11}\mathrm{Li},$ there is a strong dipole contribution associated with attractive but not a fully-fledged resonant phase shifts, and some evidence for a $J_{\mathrm{nn}}^{\pi }{=0\mathrm{}}_2^{+}$ resonant contribution. These together form a pronounced peak at around 1–2 MeV excitation, in agreement with experiment, and this supports the use of the MST as an adequate formalism to study excited modes of two-neutron nuclear halos.

• Received 7 February 2002

DOI:https://doi.org/10.1103/PhysRevC.66.021002