题 目：N=Z nuclei - a laboratory to test neutron proton pair correlations
报告人：Ramon Wyss (Professor, KTH Royal Institute of Technology)
时 间：2019年11月4日（周一）9:00-10:00
地 点：1-401物理学科会议室
报告内容：
Pairing correlations in atomic nuclei have shown to play a crucial role to many properties, in spite of the small effect on the total binding energy. The talk will start with introductory remarks on the symmetry energy in atomic nuclei, giving a different interpretation from what is found in standard textbooks.
It will then move on to the specific properties of N=Z nuclei, where neutron and proton occupy near degenerate orbitals.
This specific situation enables two different kind of Cooper pairs to be formed, that either have isospin T=0 and intrinsic spin S=1 or T=1 and S=0. It is shown that both condensates can coexist and generate a wavefunction that is a coherent superposition of both coupling modes. The effect of isospin excitation is then studied and its effect on the pair correlations. A Meissner effect in isospin is the resulting from those excitations. The formalism of approximate projection and symmetry restoration is discussed.
报告人简介：
国际著名的理论核物理学家，瑞典皇家工学院教授，北京大学名誉教授，上海交通大学、四川大学客座教授。2002-2016年曾担任瑞典皇家工学院副校长，现任西班牙教育部、中国教育部海外评审专家、芬兰科学院海外评审专家。在原子核物理研究领域的主要贡献是发展了位能面（Total Routhians (energy) Surface calculations）计算方法，并将其应用于研究原子核高自旋态、原子核形状、对关联，α衰变、质子衰变等，取得了丰硕的研究成果，已发表超过300篇论文、H-factor超过60。
