陽に解かずに準位の交差を調べる

誰かこれを読んで面白いかどうか教えて．

1. Is there a way to predict the total number of (avoided) crossings in the spectrum?
2. Is there a systematic way to locate all the (avoided) crossings in the spectrum?
3. Is there a way to identify the physical mechanisms responsible for the occurrence of (avoided) crossings in the spectrum?
4. Can the degeneracies - if any - in the spectrum be thought of as crossings?
5. Sometimes the crossings are hard to discern in the spectrum - can they be visualized in a clearer way?

In this article we employ an algebraic method that addresses these basic questions as well as some others. It allows for a simple but systematic approach to (avoided) crossings. In describing this approach we reintroduce to the study of (avoided) crossings a very useful but perhaps neglected mathematical tool, the discriminant.

↑はAm. J. Phys.に投稿されたチュートリアルだけど，一応，元はPRL & PRA2本の続き物みたい．