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[en] Relativistic one-electron ions serve as a tool for probing the description of many-electron systems by means of pseudorelativistic operators. The two operators considered are the Chandrasekhar operator which allows for relativistic kinematics in place of the Laplace operator, and the no-pair Brown-Ravenhall operator which results from a projection of the Dirac operator onto the electronic subspace. When the ions move in a locally bounded magnetic field of the type (0,0,B(vertical stroke x1 vertical stroke d+ vertical stroke x2 vertical stroke d)) with d≥0, both pseudorelativistic operators obey a scaling property which relates an increasing field B to a decreasing particle mass. It is strictly shown that, when B goes to infinity, the binding energy of the ground state (existing as a discrete state for d≤d0 where d0 increases with nuclear charge) increases with a power law Bs with s=1/(2+d). This contrasts the logarithmic increase with B in the nonrelativistic (d=0) case.
[en] The direct interaction of nuclei with superintense laser fields is studied. While direct laser-nucleus interactions have often been dismissed, we demonstrate that present and upcoming high-frequency laser facilities do allow for resonant laser-nucleus interaction. These direct interactions may be utilized for the model-independent optical measurement of nuclear properties or the preparation and control of nuclear states. We further study non-resonant direct laser-nucleus interactions such as the dynamic nuclear Stark shift. While electric dipole-allowed transitions in nuclei correspond most closely to atomic quantum optics, it is shown that in nuclei non-electric-dipole transitions are promising candidates. perspectives for the field of nuclear quantum optics are given
[en] The Unitarity Correlation Operator Method and the Similarity Renormalization Group are powerful techniques for the derivation of effective interactions from current realistic NN potentials like Argonne AV18 or the chiral N3LO forces, which are suitable for a wide range of many-body methods, including Hartree-Fock(-Bogolyubov) (HF/HFB), Many-Body Perturbation Theory, RPA and quasi-particle RPA. We discuss nuclear structure calculations based on these interactions, including three-body forces via contact terms or corresponding density-dependent two-body forces. We primarily focus on open-shell nuclei and the treatment of pairing phenomena in an HFB framework, discussing pairing gaps in isotopic and isotonic chains. The systematic connection to the free NN problem offers new insight into open questions regarding nuclear superfluidity, e.g., the importance of surface vibrations. The impact of pairing correlations on collective excitations is addressed in a QRPA framework, and tentative results are shown, for instance, for the supposed Pygmy dipole resonances in the tin isotopes.
[en] The study of the density dependence of the nuclear symmetry energy is very important for understanding many phenomena in both nuclear physics and astrophysics. We study the isospin dependence of in-medium nuclear effective interactions and the equation of state of neutron-rich nuclear matter, i.e., the density dependence of nuclear symmetry energy using the relativistic density-dependent hadron-field theory (DDRH). The DDRH approach allows a fully self-consistent calculation of the equation of state and the symmetry energy at any proton-to-neutron fraction on a fully microscopic level. We present the results of our calculation for the density dependence of nuclear symmetry energy focusing on the features such as an isospin effects in nuclear matter and behavior at low and high density.