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Abstract
摘要 |
Nuclear collective motion is characterized, to some extent, by the isospin degree of freedom. In isoscalar states, neutrons and protons move in phase, at variance with the case of isovector states. The isovector giant dipole resonance (IVGDR), the best known example of isovector motion. It can be expected that from the study of such a motion information about the symmetry energy can be extracted. In this contribution, we will argue that this is indeed the case, and yet one is sensitive mainly to the symmetry energy close to (usual) saturation density. With these premises, we will then discuss the microscopic properties of other isovector states and the hopes for a better determination of the symmetry energy. In particular, we will first focus on the so-called "pygmy" dipole states. For these states, we will discuss the collectivity, isospin character and relationship with the symmetry energy. Finally, new calculations on the isovector quadrupole resonance (IVGQR) will be discussed: the microscopic properties of this mode, the isospin purity, and the experimental perspectives will be highlighted. We will finally discuss whether the information we have extracted is consistent with other experimental and theoretical findings. |
