Esra Yüksel

Insights into the properties of dense, neutron-rich matter emerge from the interplay between nuclear experiments and astrophysical observations. Measurements of parity-violating electron scattering on 48Ca (CREX) and 208Pb (PREX-2), together with electric dipole polarizability data, offer stringent probes of isovector dynamics in nuclei. In this study, a set of relativistic energy density functionals is employed to investigate how these nuclear signatures correlate with neutron star observables, such as stellar radii and tidal deformabilities. By confronting the theoretical predictions with data from both terrestrial experiments and multimessenger observations—including the gravitational wave event GW170817—constraints are derived on the symmetry energy and the high-density behavior of the equation of state. The analysis highlights the influence of including the fourth-order term in the isospin-asymmetry expansion of the energy density on neutron star radius and tidal deformability predictions. At the same time, discrepancies between constraints from CREX and PREX-2 underscore the need for improved experimental precision and additional astrophysical input to refine our understanding of dense matter.

Nuclear ground state and collective excitation properties provide a means to probe the nuclear matter equation of state and establish connections between observables in finite nuclei and neutron stars. Specifically, the electric dipole polarizability, measured with high precision in various neutron-rich nuclei, serves as a robust constraint on the density dependence of the symmetry energy. In this Letter, we employ a class of relativistic energy density functionals in a twofold process: first, to link the electric dipole polarizability from recent experiments to the slope of the symmetry energy, and second, to translate this information into constraints on the tidal deformability and radii of neutron stars, in connection with multimessenger astrophysical observations from pulsars and binary neutron stars. We provide compelling evidence that the electric dipole polarizability represents a key nuclear observable to probe the neutron star properties. By significantly reducing the uncertainties in the mass–radius plane, our findings also align with recent multimessenger observations.

Describing the properties of highly excited or hot nuclei remains as a major challenge both for nuclear theory and experiment. We developed self-consistent finite-temperature relativistic quasiparticle random phase approximation (FT-RQRPA) using the relativistic energy density functional with point-coupling interaction to study temperature effects on electromagnetic transitions. We investigate electric dipole (E1) and magnetic dipole (M1) transitions in calcium and tin nuclei at temperatures from T = 0 to 2 MeV. Our results show that both E1 and M1 responses change with temperature, with E1 strength undergoing slight modifications and new low-energy peaks emerging due to thermal blocking. The M1 strength shifts significantly to lower energies, and new M1 states emerge that are forbidden at zero temperature. These findings can be important for modeling gamma strength functions in astrophysical nuclear reactions.

An enhanced electric octupole (E3) strength of 45(5) W.u. has been measured for the 3 − → 0 + transition in Gd 150 , providing direct evidence for large octupole collectivity in this nucleus. The value was determined following two sensitive experiments, to measure the mean lifetime of the J π = 3 − level and the weak E 3 decay branch direct to the ground state. The systematics of the E 3 strength across the Gd isotopic chain reveals that enhanced octupole collectivity is obtained for Gd 150 . The increasing low-lying octupole strength in the Gd isotopes is analyzed with five state-of-the-art theoretical models. It is found to be best reproduced by quasiparticle random phase approximation calculations, providing a good understanding of octupole collectivity in the rare-earth region.