Studying deformation in one-neutron halo nuclei using halo effective field theory

Halo nuclei are exotic nuclear structures found far from stability near the dripline. Unlike stable nuclei, they exhibit a large matter radius. This peculiar feature is the result of their strongly clusterised structure. Halo nuclei can be seen as a compact core to which one or two valence neutrons are loosely bound. Due to the quantum tunnel effect, they exhibit a high presence probability at a large distance from the other nucleons. Being located far from stability halo nuclei are mostly studied through reactions. To describe these reactions, it is essential to have reliable few body models of halo nuclei. This can be achieved by resorting to the halo effective field theory (halo-EFT).

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In this talk, I present a new structure model to account for deformation in one-neutron halo nuclei. I develop the so-called “halo-EFT particle-rotor model” to describe deformed one-neutron halo nuclei using halo-EFT interactions. I solve the resulting coupled-channel Schr\"odinger equations, for both bound and scattering states, using the R-matrix method on a Lagrange mesh. This allows to study the impact of deformation on wave functions and scattering phase shifts, for both bound and resonant states. Reactions observables such as E1 strengths and Coulomb breakup cross sections are also analysed. I illustrate these calculations for the typical one-neutron halo nucleus, $^{11}$Be, for which extensive data are available, including some high-precision ab initio calculations. This approach paves the way for a more general study of heavier one-neutron halo nuclei for which deformation plays a major role. In this spirit, I will also show some preliminary results for $^{17}$C and $^{19}$C.