Halo structure of ¹⁷C

Abstract.

¹⁷C has three states below the ¹⁶C + n threshold with quantum numbers $J^{P}=3/2^{+}, 1/2^{+}, 5/2^{+}$. These states have relatively small neutron separation energies compared to the neutron separation and excitation energies of ¹⁶C. This separation of scales motivates our investigation of ¹⁷C in a halo effective field theory (Halo EFT) with a ¹⁶C core and a valence neutron as degrees of freedom. We discuss various properties of the three states such as electric radii, magnetic moments, electromagnetic transition rates and capture cross sections. In particular, we give predictions for the charge radius and the magnetic moment of the $1/2^{+}$ state and for neutron capture on ¹⁶C into this state. Furthermore, we discuss the predictive power of the Halo EFT approach for the $3/2^{+}$ and $5/2^{+}$ states which are described by a neutron in a D-wave relative to the core.