2009-08-012024-05-17https://scholars.lib.ntu.edu.tw/handle/123456789/686092摘要：本計畫中我們想要對付兩個弦論中的重要問題。第一個問題是要推廣 non-Abelian 1-form 對稱性（Yang-Mills 理論）為 non-Abelian n-form 對稱性。此一推廣的對稱性 應該可以適用於 M5-branes 重疊在一起的低能量等效理論。另一個重要的問題是要研 究在隨時間變化的背景中的弦論。我們要採取兩個不同的途徑：AdS/CFT對偶性及 light-like linear dilaton 背景。第一個途徑幫我們把弦論的問題轉換成場論的問題，雖然 場論的問題也不容易，但是比弦論簡單。第二個途徑是去深入研究最簡單的隨時間變 化的背景。這兩種途徑有互補的關係，我們希望至少有一種方法可以得到有意義的結 果。 <br> Abstract: In this project we intend to attack two important problems in string theory. The first problem is concerned with how to generalize the notion of non-Abelian 1-form gauge symmetry (Yang-Mills theory) to non-Abelian n-form gauge symmetry. This generalized gauge symmetry is expected to appear for the low energy effective action of coincident M5-branes. Another important problem we want to study is string theory in time-dependent backgrounds. We take two different approaches: AdS/CFT duality and light-like linear dilaton background. The first approach is to transform the string theory problem to a field theory problem, which is still highly nontrivial but much easier. The 2nd approach is to study the simplest time-dependent background in detail. These two approaches are complementary and we hope to make progress in at least one of the two directions.