Charge radii in covariant density functional theory: from simple physics to complex features

by Anatoli Afanasjev (Mississippi State University)

Tuesday 4 Jul 2023, 16:00 → 17:00 Europe/Zurich

The nucleus is described as a system of A nucleons interacting via the exchange of different mesons in covariant density functional theory (CDFT). This is the state-of-the-art relativistic version of density functional theory. I will start my presentation from basic features of the CDFT and then I will focus on the physics of charge radii.
First, the role of proton-neutron interaction and occupied neutron states in the buildup of differential charge radii will be illustrated on the example of spherical Pb isotopes. Second, the results of systematic global investigation of differential charge radii within the CDFT framework will be presented. The analysis of absolute differential radii of different isotopic chains and their relative properties indicate clearly that such properties are reasonably well described in model calculations in the cases when the mean-field approximation is justified. The sources of the discrepancies between theory and experiment will be discussed. Then, I will discuss odd-even staggering (OES) in charge radii and its physical origin. It is usually assumed that pairing is a dominant contributor to OES. However, our analysis paints a more complicated picture. It suggests a new mechanism in which the fragmentation of the single-particle content of the ground state in odd-mass nuclei due to particle-vibration coupling provides a significant contribution to OES in charge radii. Finally, the connections between the physics of nuclear charge radii and atomic and high-energy physics will also be discussed.