Differential charge radii: Proton-neutron interaction effects

The analysis of self-consistency and proton-neutron interaction effects in the buildup of differential charge

radii were carried out in covariant density functional theoretical calculations without pairing interaction on the

example of selected configurations in the Pb isotopes [1]. The proton-neutron interaction of neutron(s) added to the

neutron N = 126 core and the protons forming the Z = 82 proton core is responsible for a major contribution to

the buildup of differential charge radii. It depends on the products of proton and neutron wave functions and thus

on their nodal structure. This interaction leads to a redistribution of single-particle density of occupied proton

states which in turn modifies the charge radii. The microscopic origin of this redistribution and its consequences

for differential charge radii were investigated for the first time. Self-consistency effects affecting the shape of

proton potential, total proton densities and the energies of the single-particle proton states provide only minor

contribution to differential charge radii. This work is a continuation of our efforts to understand the charge radii in

the framework of covariant density functional theory [2].