Recently there has been significant interest in applying the methods of effective field theory to halo nuclei. In this talk I will present two recent studies in this direction.
First, I discuss the one-neutron halo nucleus 11Be within an EFT in which the degrees of freedom are the 10Be core and a neutron. The 11Be nucleus has a shallow 1/2+ and a shallow 1/2- state, and so an EFT involving both resonant s-wave and resonant p-wave interactions is needed to describe it. At leading order this EFT contains three parameters in the two-body sector, all of which can be fixed using 11Be structure data. I will show the resultant EFT prediction for the dissociation spectrum obtained from Coulomb excitation of the 11Be nucleus into 10Be plus a neutron, and compare to recent experiments. This facilitates an extraction of the s-wave scattering length and effective range and the p-wave scattering volume that parametrize the scattering of a neutron from a 10Be nucleus.
Second, I describe recent work on the two-neutron halo nucleus 6He. In this case the degrees of freedom are a 4He core and the neutrons. While the neutron-neutron interaction is resonant in the s-wave, the 4He-n interaction is resonant in the p-wave, and it is the combination of these mechanisms that generates 6He binding. I will discuss the three-body equations which describe the 6He bound state at leading order in this EFT, and show that they predict a ground-state energy that diverges as the cutoff in the EFT is removed. This indicates that the 4He-n-n system needs a three-body contact interaction to be properly renormalized at leading order. We adjust the coefficient of this operator to reproduce the 6He ground-state energy, and calculate its running as a function of the cutoff. The Faddeev components that result from this procedure then have low-momentum parts which are cutoff independent. The correlations amongst 6He properties that result from this successful renormalization will be indicated.