Constraining low-energy proton capture on beryllium-7 through charge radius measurements

In this paper, we point out that a measurement of the charge radius of boron-8 provides indirect access to the S-factor for radiative proton capture on beryllium-7 at low energies. We use leading-order halo effective field theory to explore this correlation and we give a relation between the charge radius and the S-factor. Furthermore, we present important technical aspects relevant to the renormalization of point-like P -wave interactions in the presence of a repulsive Coulomb interaction.