Properties of Lithium-11 and Carbon-22 at leading order in halo effective field theory

Abstract

We study the 11Li and 22C nuclei at leading order (LO) in halo effective field theory (Halo EFT). Using the value of the 22C rms matter radius deduced in Ref. [1] as an input in a LO calculation, we simultaneously constrain the values of the two-neutron (2n) separation energy of 22C and the virtual-state energy of the 20C−neutron system (hereafter denoted 21C). The 1−σ uncertainty of the input rms matter radius datum, along with the theory error estimated from the anticipated size of the higher-order terms in the Halo EFT expansion, gives an upper bound of about 100 keV for the 2n separation energy. We also study the electric dipole excitation of 2n halo nuclei to a continuum state of two neutrons and the core at LO in Halo EFT. We first compare our results with the 11Li data from a Coulomb dissociation experiment and obtain good agreement within the theoretical uncertainty of a LO calculation. We then obtain the low-energy spectrum of B(E1) of this transition at several different values of the 2n separation energy of 22C and the virtual-state energy of 21C. Our predictions can be compared to the outcome of an ongoing experiment on the Coulomb dissociation of 22C to obtain tighter constraints on the two- and three-body energies in the 22C system.