Charge radii of potassium isotopes in the RMF (BCS)* approach

We apply the recently proposed RMF (BCS)* ansatz to study the charge radii of the potassium isotopic chain up to K-52. It is shown that the experimental data can be reproduced rather well, qualitatively similar to the Fayans nuclear density functional theory, but with a slightly better description of the odd-even staggerings (OES). Nonetheless, both methods fail for K-50 and to a lesser extent for K-48,K-52. It is shown that if these nuclei are deformed with a beta(20) approximate to -0.2, then one can obtain results consistent with experiments for both charge radii and spin-parities. We argue that beyond-mean-field studies are needed to properly describe the charge radii of these three nuclei, particularly for K-50.