Neutron distribution, electric dipole polarizability and weak form factor of 48Ca from chiral effective field theory*

How large is the $^{48}$Ca nucleus? While the electric charge distribution of this nucleus was accurately measured decades ago, both experimental and \emph{ab initio} descriptions of the neutron distribution are deficient. We address this question using \emph{ab initio} calculations of the electric charge , neutron, and weak distributions of $^{48}$Ca based on chiral effective field theory. Historically, chiral effective field theory calculations of systems larger than 4 nucleons have been plagued by strong systematic errors which result in theoretical descriptions that are too dense and over bound. We address these errors using a novel approach that permits us to accurately reproduce binding energy and charge radius of $^{48}$Ca, and to constrain electroweak observables such as the neutron radius, electric dipole polarizability, and the weak form factor.