Orateur
Description
Excitations across the Z=20 shell gap ($1d_{3/2} -
1f_{7/2}$) have been studied within the framework of the cranked relativistic mean field (RMF) model (Physics Reports 322, 1 (1999)). A systematic increase in the discrepancy between theoretical predictions and experimental shell gap energy differences was observed with increasing isospin asymmetry. To address this limitation, the RMF Lagrangian was modified by incorporating additional constraints on shell gap energies during the parameter optimization procedure. The strength of the constraint was determined following the prescription of (Phys. Rev. C 6, 532 (1972)). A similar approach has also been adopted within the non relativistic framework (Phys. Rev. C 71, 024305 (2005)).
The revised parameter set exhibits a significant reduction in the discrepancy between theoretical and experimental shell gap energy differences compared with the widely used NL1 and NL3* parameterizations. In particular, a notable improvement in the description of single particle energies around $^{40}\text{Ca}$ is achieved without affecting the bulk nuclear properties. These results demonstrate the importance of incorporating shell gap constraints for improving the predictive power of RMF models in nuclear structure studies.