Many-body systems interacting by random interactions
Yu-Min ZHAO
Saitama/Nanjing
日時：2002年12月06日（金） 14:00-
場所：東北大学理学部物理A棟504号室
The ground state spins of even-even nuclei are always 0 without anexception, which is believed to be a consequence of the attractiveshort-range interaction. However, it was recently discovered thatspin 0 ground state (0 g.s.) dominance can be found in many-bodysystems with random interactions. This discovery is very interesting because, just as pointed out in a paper by Johnson, Bertsch, Deanand Talmi, we are interested in asking: "how arbitrary can an interactionbe and still `be` nuclear physics?" It is well known that the low-lyingexcitations of quite a few many-body systems, such as atomic nucleior molecules, often display a pattern suggestive of group symmetries,such as rotational or vibrational bands, despite that these many-bodysystems are so different, complicated. The symmetries are quite unclearfrom those complicated interactions. This raises a question that how muchthese "key" properties can be remained if we relax our interactions in ourcalculation? or we ask for a specific case: what type of interactions produce a generic collectivity, say, rotation? The result that dominance of 0 a.s. separated with a gap from the excited states may be obtained by random interactions indicate that at least one of the key properties (0 g.s. dominance) of nucleus does not really require our previous assumptions: the strong attractive pairing. Then we can ask: what is the origin of this robust observation? Many efforts were made to understand this unexpected discovery. There are also a lot of works related to this, e.g., generic collectivity in systems with random interactions, the behavior of average energies etc. In my seminar I shallpresent the recent development, in particular the progresses contributed by my collaborators and myself, in understanding the 0 g.s. dominance of many-body systems, and related topics, such as generic rotation and other regular features of fermions and boson systems, etc.
＊ 時間が変更になりました。ご注意願います。＊１６：００より茶菓を用意致します。