Halo structure of $^{17}$C

Abstract

17 C has three states below the 16 C + 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 16 C. This separation of scales motivates our investigation of 17 C in a Halo effective field theory (Halo EFT) with a 16 C 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 16 C 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.